Just pilling on some concrete examples, awesome-gemini is definitely the best place to start looking. There are both converters for the gemtext format and gateways for the protocols.

For format conversion tools, awesome-gemini already lists a handful of tools.

From the gemini side there are some gateways for specific websites operated by various people

• BBC news gemini://freeshell.de/news/bbc.gmi
• The Guardian gemini://guardian.shit.cx/world/
• Lots of others gemini://gemi.dev/cgi-bin/waffle.cgi

These work pretty well for me. I think there were public gateways to open http pages from gemini, but I can't recall one from the top of my head.

Some of the gemini browsers support gemini proxies to access http(s) content. You can run it in your own machine. Duckling is the only one I'm familiar (but see the awesome list for more)

• https://github.com/LukeEmmet/duckling-proxy

Conversely, to access gemini pages from a web browser portal.mozz.us hosts a gateway (just place whatever gemini link you want in the box).

One big privacy caveat of using gemini proxies for this is that while this may improve your privacy with regards to javascript/cookies it will reduced it because it makes your behaviour more identifiable from the point of view of the websites you visit (i.e. your proxy is clearly not a browser making it unusual).