The Constrained Restful Environments (CoRE) Working Group is an IETF working that provides a framework for REST applications intended to run on constrained IP networks.
You can see the current drafts on the CoRE WG Github as well as join the mailing list to participate. Presentations, agendas and minutes from past meetings can be found in the WG Materials repository.
We will be having virtual interim meetings on 2024-12-18 and then every other week starting from 2025-01-15 until IETF 122.
There is a number of available implementations of CoAP.