

Zen is basically Firefox with different UI. It is a security/privacy downgrade from Librewolf. You can configure Zen to have the same security/privacy settings by putting about:config in the URL bar change some of the toggles.
Use either the Arkenfox (also available in the interactive live viewer online) or Phoenix user.js as a template. Basically: disable WebGL, set WebRTC to disable nonproxied udp, disable JavaScript JIT, enable privacy.resistFingerprinting (optionally enable privacy.resistFingerprinting.letterboxing for screen fingerprint protection) and some other things.
Phoenix has some configs for Zen iirc which you can just patch. It is less strict than Librewolf when it comes to fingerprint protections (softening some of RFP’s protections).
If you want to test that the fingerprint protections are working, use this test site by Arkenfox called TorZillaPrint.




I would go with (semi)rolling, either openSUSE Tumbleweed/Slowroll or Fedora. I prioritize fast updating distros because they are better for security (many vulnerabilities go unnoticed because the full scope isnt understood and they are deemed normal bugs), and (unlike Windows) updates on Linux are a good thing, bring new features, crash/bug fixes, and optimizations.
Fedora is very popular, has wide software support, and is very stable. openSUSE is also still pretty popular, (even its rolling edition) is quite stable as well, has good software support, and YaST allows you to do graphical administration on your system. Both take security seriously and use SELinux for security policies.
If you care about security, use Brace for automatic system hardening. It has been developed for years by the former DivestOS dev Tavi, supporting many distros.