Calio is a great and useful lib, I especially appreciate your Codec implementation on Forge side and is looking forward to use it outside the Origins mod :)
However the old unified jar way doesn't support this kind of usage :(
Now that Forge had finally implemented the JarJar feature on 1.18.x and 1.19.x, I believe it will be nice make Calio (and maybe Apoli?) a independent lib mod and have its own maven release (Jitpack may be a good choice) just like the Fabric version.
Considering 1.18.x is still supported by the community, it would be better if this request also being accepted on 1.18.x ;) (I know asking for 1.18.x update is actually an annoying backport request, sorry for that if you dislike it)

The plan is to release with JiJ for 1.19 but subprojects are not currently supported, so I need to make the gradle script manually.
But yeah, the goal is to use JiJ whenever I get enough time to peacefully coerce a system that is absolutely not designed for subprojects into working properly.

I'll see if what I can do for 1.18. And I'll at least try to get a release done, but I'll test the build script on my current workspace (i.e. 1.19)

Thanks for the quick reply :)
Btw I wonder if it's possible to reimplement Calio back to 1.16.x (especially the possibility to keep the Codec stuff)? This is not a request, I may make a fork and try to work it out myself if needed.

As far as I'm aware, calio doesn't rely too much on Java 17 features, so you should be good, but some things may need to move around since forge changed a lot from 1.16-1.19

If I didn't make a horrible mistake in my PR, and if they are willing to accept it, FG should have the ability to use subprojects with JarJar at some point.

JiJ is done for 1.19, you can find the jars in the description of the latest release.
You'll probably need to use flatDirs for now, since I can't find artifact renaming anywhere within gradle.