Looks very tough considering how much complicated a modern browser is. There is Ladybird project but it's expected to be in Alpha stage by 2026.

If you can get the cool kids to migrate to a new, simpler, protocol... (or maybe it's too late and this is what we've got - after all, Gemini was a bust).

I have very little faith in people building a lot of new security infrastructure in C++ at this point in history.