There's actually already portal.mozz.us as well as proxy.vulpes.one, both of which are Gemini "portals" ala gopher.floodgap.com. I actually began to try and write an addon to open gemini:// links in Firefox based on Overbite, but I couldn't figure it out (and I'd have to change the gemini protocol to something like gemini+web, due to Firefox limitations).
Just because you can do that, does not make it part of the Web -- it's still a different space. Those portals are basically web-based clients to the protocol, which means they're still bound by the rules of the protocol -- they're not going to have JS in them, for example.
