Chrome is the only alternative unless you have access to Safari. Brave, Opera, Edge, etc are all Chromium and will all deprecate Manifest V2 eventually. The V2 mess is just one example of how Google can continue to stangle the web even if you're not using Chrome itself.
Epiphany on Linux is a pretty straightforward Webkit browser. Konqueror still exists. Ladybird is up and coming. Servo is still making progress.
>Chrome is the only alternative
The future looks pretty clear to me. We will have to use two browsers. One government approved, google (or some other thing) vetted browser for all the official and banking stuff. One other for all the other causal stuff.
This would be bundled as a single package, with something like firefox containers automatically switching to the "approved" browser based on domain loaded in the tab.
Chrome != Chromium engine
Most of the Chromium-based browsers remove Google's telemetry and integrations, so if someone has a problem with Chrome "looking over my shoulder", then they have many more alternatives.
And sure, Manifest V2 will disappear in all those forks, but many browsers have built-in adblocker instead, for example both Opera and Brave claim to. And other than adblockers, what else is lost in Manifest V2?
Mind you, I am still using Firefox, but saying "the only alternatives are Chrome and Firefox" is completely incorrect.