[off topic on]
AFAIK, there should be a way to easily install or emulate X11 on a Mac (so, creating for Mac a fpGUI application could be possible).
So, another interesting question would be: can an native fpGUI application run under WSL2 too? Answer: no need for WSL2, because fpGUI controls can be compiled towards X11 or towards MS-Windows CGI graphic layers (it's brilliant).
[off topic off]