Short description: "Neocities is a commercial web hosting service for static pages. The service's expressed goal is to revive the support of free web hosting of the now-defunct GeoCities." WikiPedia
Optional API documentation URL: https://neocities.org/api
You can do something similar to how it works with Reddit. The user makes a post under their profile and Keyoxide looks for that comment.
For example, the user posts a comment under their own profile page that says something like "OpenGPG key: FINGERPRINT". The notation would be something like "email@example.com=https://neocities.org/site/USERNAME?event_id=COMMENT_ID"