That's right. Moreover, the activity no the repo has been a bit stagnant (no disrespect to the maintainers, they are likely busy with other projects or life). Other projects have opted to fork the repo, rewrite the module repo path, and maintain their fork (e.g. https://github.com/tailscale/ssh/, but I've seen many others too). I didn't want to maintain a fork, so a copy under internal/ in my own repo means it's firm-fork (between soft and hard) where I can confidently break its APIs I'm the only one depending on without worry. It will slowly morph to fit the needs of the project only.

The maintainers gliderlabs/ssh have plans for a new version with more ergonomic APIs but the work hasn't started yet. I didn't want to wait either.