https://github.com/AppImage/type2-runtime/issues/77
I think I fixed it, now it builds inside Alpine chroot and correctly copied out before chroot deleted (debuggin this was ... slow)
I see it uses libfuse3 so hopefully there will be no need for libfuse2 workaround on new Debian 11, etc.
But I have not tried to use this runtime part anywhere yet.
Build takes around 400 mb in /tmp