I see flatpak and snap as potential solutions to the problem of distributing proprietary software to Linux. Its in that usecase that I really want sandboxing an

I see flatpak and snap as potential solutions to the problem of distributing proprietary software to Linux. Its in that usecase that I really want sandboxing and where the current solutions are lacking. Right now I'm most happy with Firejail for sandboxing proprietary applications. It doesn't solve the packing problem but seems to do the best job at actually limiting what applications can do.