I use firejail. At least the browser cannot see arbitrary files in my home directory, like ssh or gpg keys, password manager, and everthing else. To share files

I use firejail. At least the browser cannot see arbitrary files in my home directory, like ssh or gpg keys, password manager, and everthing else. To share files between the browser and the rest ~/Downloads can be used. Disclaimer: Critics say firejail is too complicated to be audited and adds too much attack surface of its own.