How to restrict browser Firefox or Opera?

Question

ubuntu

I have been using Ubuntu for many years. Lately, I've been concerned about safety.
Computers are weak, you can not use virtual machines.
I know that there is some kind of sandbox in Arch.
Can it also be done in Ubuntu?
Specifically, it is necessary that the browser sees ONLY its own profile, which is not placed by default.
There is nothing else (no temporary, no downloads, no documents).

Answer 1

firejail , firejail