Along those lines, a separate command like uv-pip might work. Subcommands are fun but not necessarily the best UX (and it seems like this is meant as a stopgap, not a long-term interface). There’s precedent in the cargo family (e.g. cargo-fmt) if that makes it more acceptable 
Using the name pip at all will always have the potential to confuse people, though. I don’t think confusion can be entirely avoided, though–people can get confused about anything.