Photon is available for any instance at https://phtn.app.
Alexandrite is available for any instance at https://alexandrite.app.
I don't like when instances will host photon for anything other than the default interface, as then it's just a more limited, outdated version of photon and another point of failure.
I need to add language settings to communities and profiles. I really dislike how lemmy handles this though.
If you change it in lemmy-ui, it will propagate to Photon because it's an account wide setting.