For a .dev package I believe it is fine, but if you want to put it under released at some point please craft a more precise description of it.
This is in no way urgent, but it's possible we'll at some point want to release fiat-crypto, and if the released fiat-crypto depends on coqutil via bedrock2, this will then be a blocker for releasing fiat-crypto on opam.
Quoting Enrico in https://github.com/coq/opam-coq-archive/pull/914#issuecomment-535397392:
This is in no way urgent, but it's possible we'll at some point want to release fiat-crypto, and if the released fiat-crypto depends on coqutil via bedrock2, this will then be a blocker for releasing fiat-crypto on opam.