I remember doing something similar, but I just used two columns, a public uuid, and a bigint primary key that wasn't exposed to the api (this was long before uuidv7). Lacked a lot of the conveniences of using uuid everywhere, but it still handled the use case of merging different DB dumps as long as PKs were stripped out first.

And maybe I misunderstand how the hashing works, but it seems if you're looking things up by the hashed uuid, you're still going to want two columns anyway.

The conversion is reversible using the secret cryptographic key so you can turn the uuidv4s from requests into your db uuidv7s.