Curiously, what is the alternative? Chromium-based browsers?

Sorry, but I don't trust Google's push to Manifest V3.

I daily drive https://kagi.com/orion/ on mobile and will likely begin to switch on desktop as their cross platform support emerges.

for web apps I ended up going with Gnome Web, but Tangram and Ferdium are other options I'm considering

Zen is Gecko-based.