I see. Figured it was more complicated right after replying.
Just an idea: why not mounting the home area at its original place inside the container? I understand that it may clash with another directory already present on image, but you could deal with these cases, instead of trying a universal solution. I fully understand that an elegant, “all cases” solution is the way to go, but implementing some kind of “pre check” for clashes before launching the snap would suffice for most cases, don’t? If somebody places its home in a completely awkward path, they would’ve problems much earlier than launching snaps.
Anyway, thanks for you time. Will keep an eye on this, see if it is eventually solved.