Hm... I'm guessing that adding Uranium to that would make it quickly oxidize, and instead of H2O4U, you'd get mostly U3O8 (the most stable Uranium oxide) and a bunch of H2O and Hydrogen gas.

No way to know until you try

I wonder if there's any Uranium-containing compoud that would be safe(ish) to drink... (In small amounts, of course.)

It would have to be something that holds onto the Uranium atoms very tightly and also passes right through you without getting absorbed. Hmm... But the radiation aspect is always going to be a problem. No matter what other atoms it's bonded to, Uranium will still be emitting a bit of alpha radiation -- no big deal when it's outside you since the outer layers of skin block most of it, but when it's inside you, there's nothing to block that radiation from damaging the cells of your digestive tract.