Currently it looks like we support packages pinned to local paths and git urls but not archive urls. The ocaml.org project has a pin ["tailwindcss.dev" "https://github.com/tmattio/opam-tailwindcss/archive/3e60fc32bbcf82525999d83ad0f395e16107026b.tar.gz"]. Currently locking this project (after removing the package stanza from its dune-project file to workaround #10120) produces the error:

File "ocamlorg.opam", line 1, characters 0-0:
Error: Could not determine location of repository
https://github.com/tmattio/opam-tailwindcss/archive/3e60fc32bbcf82525999d83ad0f395e16107026b.tar.gz
Hint: Specify either a file path or git repo via SSH/HTTPS