I wrote this test class to get coordinates from a Google Maps share link in C# (.NET 8):

public class Test : IDisposable
{
    private readonly HttpClient _httpClient = new();

    public void Dispose()
    {
        _httpClient?.Dispose();
        GC.SuppressFinalize(this);
    }

    public async Task<string?> TryGetCoordinatesFromGoogleMapsShareLinkAsync(string shareLink, CancellationToken cancellationToken = default)
    {
        using var response = await _httpClient.GetAsync(shareLink, cancellationToken);
        var expandedUrl = response.RequestMessage?.RequestUri?.ToString();

        if (!string.IsNullOrEmpty(expandedUrl))
        {
            return ExtractCoordinatesFromExpandedGoogleMapsUrl(expandedUrl);
        }

        return null;
    }

    private static string? ExtractCoordinatesFromExpandedGoogleMapsUrl(string url)
    {
        var atIndex = url.IndexOf('@');
        string? coordinates;

        if (atIndex != -1)
        {
            var coordinatesPart = url[(atIndex + 1)..];
            var parts = coordinatesPart.Split(',');

            if (parts.Length >= 2)
            {
                coordinates = $"{parts[0]},{parts[1]}";
                return coordinates;
            }
        }
        else
        {
            var parts = url.Split('/')[5].Split(',');

            if (parts.Length >= 2)
            {
                coordinates = $"{parts[0]},{parts[1]}";
                return coordinates;
            }
        }

        return null;
    }
}