I have yet to see this genius idea in a mod.

A portable pump, handheld and it could also have tanks that can be placed in armor slots.

I would suggest 16 or 8 buckets in the handheld device and 32 or 16 buckets more in the tanks for the armor slot (could be different Tiers for this aswell). would run on XP as everything else in the mod, either that or just be free to use but more expensive to make.

Would have to be able to pump any fluids, and also fill tanks with them

im picturing something like the Ghostbuster gun or a modified version of the Crane you got in the mod allready. Perhaps even extendable arms so it reaches further out.

Recipe could include a vacuum hopper and something else.