As I read the whitepaper, it almost seemed like each logical step would need an on-chain transaction. It would be very slow to use as a back-and-forth medium, but it could be used to prove something globally for all of humanity, like the anonymized aggregate result of an election.

Useful for proving things that don't need to be fast? Yes. Useful for routine smart contracts? Probably not.

I will say that BitVM may be a good option for making more secure side chains without changing the consensus algorithm like would be needed with drive chains.