I was using renovate for a while for flake inputs however, I encountered a few bugs since the internal architecture made it quiet complex to implement nix flake update <input>. So I created a while a go this github action that now powers flake upates in all my projects:
I made a similar action also for gitea as well: GitHub - Mic92/update-flake-inputs-gitea
The main difference over GitHub - DeterminateSystems/update-flake-lock: Automatically refresh your Nix Flakes. is that both create one PR per flake input, since in significant complex repos breakages in a single flake can potentially block all the others. It also can auto-merge pull requests after the CI passes.
will it be possible at some point to update some flake inputs together? For example, I often find myself updating nixpkgs and home-manager at the same time.