The "most Kotlin-esque" way I found to do this sort of formatting is:

"%,.2f".format(Locale.GERMAN, 1234.5678)      // => "1.234,57"
"%,.2f".format(Locale.ENGLISH, 1234.5678)     // => "1,234.57"

"%,.2f".format(1234.5678)                     // => "1,234.57" for me, in en_AU

Note though that even though this is Kotlin's own extension method on String, it still only works on the JVM.

For those looking for a multiplatform implementation (as I was), mp_stools is one option.

Example:

import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.util.*;  

public class AddZeroToOneDigitDecimal{

     public static void main(String []args){
       System.out.println(customFormat(3434));
       System.out.println("----------");
       System.out.println(customFormat(3434.34));
       System.out.println("----------");
       System.out.println(customFormat(3434.3));
     }

     public static String customFormat(double d){

        String result =  formatter.format(d);
        return (result.replace(".00",""));
     }
     
     private static DecimalFormat formatter;
     private static final String DECIMAL_FORMAT = "#,###,##0.00";
     private static DecimalFormatSymbols formatSymbols = new DecimalFormatSymbols(Locale.ENGLISH);
    
     static {
         formatSymbols.setDecimalSeparator('.');
         formatSymbols.setGroupingSeparator(' ');
         formatter = new DecimalFormat(DECIMAL_FORMAT, formatSymbols);
     }
}

Simplified

 val formatter = DecimalFormat("#,###,##0.00");
 return formatter.format(value).replace(".00","");

I know some of the above solutions work perfectly but I want to add another solution that uses ceil and floor concept, which I think is optimized for all the cases.

If you want the highest value of the 2 digits after decimal use below code.

import java.math.BigDecimal 
import java.math.RoundingMode
import java.text.DecimalFormat

here, 1.45678 = 1.46

fun roundOffDecimal(number: Double): Double? {
    val df = DecimalFormat("#.##")
    df.roundingMode = RoundingMode.CEILING
    return df.format(number).toDouble()
}

If you want the lowest value of the 2 digits after decimal use below code.

here, 1.45678 = 1.45

fun roundOffDecimal(number: Double): Double? {
    val df = DecimalFormat("#.##")
    df.roundingMode = RoundingMode.FLOOR
    return df.format(number).toDouble()
}

Here a list of all available flags: CEILING, DOWN, FLOOR, HALF_DOWN, HALF_EVEN, HALF_UP, UNNECESSARY, UP

The detailed information is given in docs

You indeed might use java.text.NumberFormat to achieve your goal. The following should work is quite close to your example Swift code.

// you can change the separators by providing a Locale
val nf = java.text.NumberFormat
    .getInstance(java.util.Locale.GERMAN)
nf.minimumFractionDigits = 0
nf.maximumFractionDigits = 2
   
// you may want to change the rounding mode
nf.roundingMode = java.math.RoundingMode.DOWN
    
println(nf.format(0)) // 0
println(nf.format(1)) // 1
println(nf.format(1.2)) // 1,2
println(nf.format(1.23)) // 1,23
println(nf.format(1.234)) // 1,23
println(nf.format(12.345)) // 12,34