Well, what's actually the reason for this split? What problem does it try to solve?
@kugel- Has [described](https://github.com/geany/geany/issues/3015#issuecomment-975987322) it this way:
Store the session part elsewhere (your suggestion is nice), so that the remaining project part is largely static and invariant across systems, so that can be checked in.
Likewise, my goal for the session split is to be able to store geany.conf in my personal "dotfiles" repository that I sync between laptop and workstation.
As I've [noted](https://github.com/geany/geany/issues/3015#issuecomment-979876697), there are ways to preserve your use case.