Robin
Is there a better way to have a newer (locale) gcc, without changing the system wide packages/libraries?
Normally you can install gcc (and also g++) in multiple versions parallel on your system. Unfortunately debian bookworm repos don’t provide recent gcc, merely gcc 11 and 12 are present and can be installed, not 15.2, but you can try compiling it from sources and install it locally then. No extra container should be needed for this to work.
For selecting what version is the default in your system, go into antiX Control Centre, section “System”, therein click open “Alternatives” and therein select “CC” or “CPP” or similar from the list in the left column, which allows then in the right field to preselect what gcc version will be used.
Windows is like a submarine. Open a window and serious problems will start.