This mod is really missing for 1.21.x, are there any plans to develop it for this version?

Sorry for the delay, I'm really busy currently with IRL things, so not had much time to work on it. It's not on GitHub currently, as it's a complete rewrite for RefinedStorage2

Makes sense, IRL first! :D

When it ready

Not to sound entitled, just interested: Why is there no 1.21.x branch with the progress?

Isn't that kinda "standard" in terms of in-dev versions of open source mods? :D

Sorry for the delay, I'm really busy currently with IRL things, so not had much time to work on it.
It's not on GitHub currently, as it's a complete rewrite for RefinedStorage2

Yes, Its planned and is in progress

Any ETA?

When it ready

has there been an update on this for 1.21.1 Neo?

Still been really busy, just moved, so have not had much time to work on it