Opensnitch is in Debian repos. Brave can be installed on amd64 computers. Firefox is easily fixed, or you can use Librewolf. To Browser is easily installed. Not much to worry about.

opensnitch: Installed: 1.5.7-1 Candidate: 1.5.7-1 Version table: *** 1.5.7-1 500 500 https://deb.debian.org/debian unstable/main arm64 Packages 100 /var/lib/dpkg/status

https://github.com/evilsocket/opensnitch/releases