I'll address some specifics (mostly since you mentioned HP zBooks and EliteBooks as I happen to have dealth with those a lot over the years), but the first thing on your list should be the obvious:

Check the user manual! It will tell you if your laptop can be charged through a USB-C port (and if so, which one), and potentially what wattages and voltages it would require on its regular DC plug.

Short version if you specifically just have HP laptops: The 150W Smart AC HP adapter will power most HP laptops you'll throw at it, although it might be still a good idea to check for anything "special" wanting more than 150. One of the product codes you can search for is 4SC18AA, this is one of the HP product codes, there are multiple depending on your plug preferences and/or availability but will give you an idea of what to look for. The AC plug part is a bog-standard C5 "Mickey" plug on the other end, so your local stores will have one that fits if you can't get the adapter with the correct AC plug for your country. I have one of those on my desk at work and any HP laptop made in the last 10 years can run off of it.

A summary of the following wall of text comes down to the fact that there are like 3-4 power supply wattages and they are largerly interchangeable.

Now with that out of the way, here's how it works with HP business laptops (ProBooks, EliteBooks and zBooks, the ProBooks have been merged with EliteBooks as of the last few generations due to a lot of overlap).

The main "incompatibility" comes from the required power - the wattage the charger is providing. This is stated both on the PC itself as well as the charger, sometimes as a straight number (in watts, W), sometimes as a voltage and an amperage (in volts, V and amperes, A). In the second case you simply multiply the two numbers to get the watts. Those numbers are often ugly as HP uses an odd voltage of 19.5V, but you don't need to worry as there are only a handful of standard wattages those come in - 45W, 65W, 150W are the three common ones, 100W and sometimes 90W is seen, and there are a couple intended for docking stations and port replicators (200W and 230W). As long as you can do the math close enough, you'll know which one it is, for example, 7.7 amps at 19.5 volts works out to 150 watts, and 3.33 amps at 19.5 volts happens to be 65 watts. Give or take, of course, but well within the tolerance.

The second incompatibility is the physical plug - HP's come in two sizes, one's about 4mm and the other is around 7. The main reason for either to be chosen is simply its size - most newer (post 2013 or so) laptops will use the smaller plug while some older models like the really old blocky EliteBooks will use the larger one. Docking stations will generally use the larger one - there are some odd exceptions like a certain flat ThunderBolt dock/replicator intended for zBooks, where the thinner connector is used, likely due to the thinner shape of that specific unit. For what it's worth, they are totally interchangeable apart from the physical size incompatibility, and I have a few adapters that I don't remember the exact origin of that accept the smaller plug to allow it to be plugged into the bigger receptacle. My best guess those came with some of the docking stations or some of the chunkier, older laptops of yore to provide the possibility to power either. Those also exist in reverse, allowing using the bigger plug with a device that requires the smaller one.

Either way, an adapter with higher wattage is not an issue, it will never overload a laptop normally using a lower wattage as it is the laptop that demands the power and the number is actually a cap on how much power the laptop can demand. The main downside of the bigger power supplies is their bulk - which is why the tiny 45W adapters exist.

And the last thing to be said about those power supplies is that laptops have generally become smarter and a lot of them are able to accept a lower wattage (basically a lower current) with various degrees of degradation, from slower charging (just like phones) to reduced performance (for the hungrier models having to run off of a small charger). I have seen some of the older zBooks - think G4 or lower - refuse to recognise the small chargers completely, but the newer models usually just warn you that "charging is slow". Some of the bulky, old 200W bricks (seriously, they are like a pound each) seem to be hit-and-miss with the newest laptops, but I suspect a lot of them are simply dying of old age. I definitely used to have a couple of those as "universal HP power supplies" a few years back the least.

Bottom line is - the 150W unit is the "one size fits almost all" solution for your HP laptop needs.

Okay, but what about USB-C and Power Delivery?

So, this one can be tricky, (check the manual!) but most HP stock, at least the office ones, have supported this for a while, an easy rule of thumb here is to check every laptop if it has the big bulky docking station connector - the support came around the time they ditched those, though I there might have been one generation with the docking connector and PD support.

In any case, the correct USB-C port will likely be next to the DC receptacle, a zBook sometimes has two next to each other next to the DC input. Those are often marked with a lightning bolt icon which makes sense, but that actually specifies that they support the ThunderBolt specification - and that does not explicitly equal USB-C Power Delivery, but often coincides.

The important part is, as of now (March 2025), the most common version of PD supports up to 100W. There is a more recent version allowing over 200W, but it is not that common yet and definitely will not be found in some random old PCs you have lying around.

This does kinda cut off the larger, thirstier devices such as the zBook (and similar workstation-class and gaming-class PCs), although, again, quite a few of the newer models are able to make do with the lower available power, capping CPU speeds and slowing down charging - perhaps not usable at full power while on such a charger, but definitely possible to charge overnight.

but what about other brands of laptops? Here's the stinger: those wattages, that voltage, and the two physical plug sizes have become more or less standardised. Dell uses 19.5V, as an example, and there are indeed adapters in 45W, 65W and 90W. The problem is, after standardising those, there had to be a way to account for the cases of a "bad" connection such as an undersized charger, and whatever the technical reasons actually were, the end result is that the DC connector actually has 3 wires - the positive and negative as is expected of DC, and a third "smart" wire. This results in a "soft" incompatibility between different manufacturers' laptops and power supplies.

This is used to let the device communicate with the power supply to learn what voltages and wattages are supported, and, in an ideal world, there would've been some proper standard like EDID with monitors that simply provides a protocol for this information exchange. Instead, the manufacturers basically just got this third wire to do with as they please - which means that each has their own "language", and a Dell power supply won't respond properly to a question asked by a HP laptop, causing the laptop to reject it altogether or at least defaulting to assuming the lowest possible power to be safe. This, of course, does have a nice side effect of being profitable. As far as I know, there are ways around that, but that's up to the individual whether they want to bother with that.