tangled.org
mvdan.cc
For example, Gerrit supports this by pushing to a special ref like refs/for/master, and GitHub has gh pr create.
I'd personally go for the former, because it's more "git native" and doesn't require maintaining and using a custom CLI. You can still add options in text form to that custom ref you push to, e.g. on Gerrit one can do refs/for/master%r=reviewer@email.com,l=some-label to assign a reviewer and add a label.
https://gerrit-review.googlesource.com/Documentation/user-upload.html
It is pretty hard to implement that in current implementation because then we need Knots to have write access to users PDS and there is no way to do that without AppPassword.
There are two proposals to resolve this issue, one has been paused due to low priority and the other is still waiting for the review.