Yeah, you are right. "Pull request" in itself could be parsed as a command, but it is a thing really. Used in a command you would say "Send pull request". Where send is the verb and "pull request" is the object. In my native language it would actually be a single word. I have seen some people write it as pull-request, which removes the ambiguity.

Note that "Merge request" doesn't solve this problem.

From a user-interface design perspective I would say it would be bad to have a button or link that solely says "pull request" or "merge request". It should probably be preceded by a verb such as view, send or process.

Also, pulling a pull request or merging a merge request is just weird and doesn't make sense.