I read there is something called firejail that does this, but according to the reviews on software manager, some have had it destroy their system or mess up their programs, so i dont want to risk that.
There was also something called bubblewrap, but it has no reviews at all.
How big risk does the firejail have and are there any other programs that are good or better for this? I already managed to mess up my system once (blackscreen after login. I think installing portmaster caused it or installing and uninstalling some software + its dependencies), but fortunately i had backup of the system so i could reverse the damage, so i’m a bit more cautious now.
Also, are there any other concerns that one should know about regarding sandboxing?
If you’re reading reviews on Software Manager, you don’t want to be messing with jails.
Just use Flatpaks, and install Flatseal for permissions control over individual packages. They are sandboxed, but with permissive defaults set by the devs, so you can use Flatseal to lock them down, then set permissions you’re comfortable with. If it breaks something in that one Flatpak, then just reverse your permissions changes. Simple.