Regarding the process: I wrote that down for community.proxmox here: What's up with proxmox.community? - #2 by felixfontein For a Keycloak collection it would be the same, up to updating the names in that process 
If there is one or more maintainer who wants to maintain that collection, that’s perfect! From c.g’s point of view, there’s no reason to not move the modules. The main reasons to not move content out of community.general in the past have been:
- There haven’t been maintainers for collections for a set of modules/plugins. (That’s still the main reason why it is not happening more often.)
- We had a rule that content from collections included in Ansible can only be moved to collections that are also part of Ansible. That prevented some moves, but we removed that rule anyway. So this is no longer preventing anything.