As all the Jams and Jellos have fluids it would only make sense if you could pump them out of their related cauldrons or into a vanilla one.

Do you play 1.20.1 or 1.21.1? they are not block entities and it's only possible in 1.21.1

1.20.1, and that is strange, as the vanilla lava, water and empty cauldron all are able to connect to at least the create pipes.

Create make special case for them and those are not handled via fluid handlers.

For any modpack maker trying to do this (or at least something similar) use Supplementries faucets.

Can you implement it for 1.21 though? I personally don't intent to update any time soon, but it would still be nice for others to have , if the environment allows it without being too hacky.

Will do