I'm working now on Wine-systemwide, an set of bash/python3 scripts to allow use one app installation by many users, but not at the same time. The issue is addressed for many poor families, whereas people share one computer.
Many things working now. I do many test and what isn't working is Time Commando from GOG installer (segfault). Desktop and documents aren't shared, but wineprefix is shared. This gives possibility of split saves/documents or settings (for example).
See more info on: https://forum.winehq.org/viewtopic.php?f=8&t=34716
I asks for permission and suggestions for/how integrate this into PlayOnLinux.