I haven't heard much about in a while, but the HTML Triptych proposal [0] is still something I hope to eventually land in browsers. HTML forms speaking to REST endpoints are a good pattern. (meaning user-aiding validation is handled via the input attributes, real validation is handled on the far side of the request, and the flow is GET /form => POST /thing => GET /thing/1) It would be a great pattern with the triptych features implemented!

[0] https://triptychproject.org/