I work with a blind developer. We create personal feature branches, file a ticket for merge requests in our ticketing system, code review them directly in the ticket or via email, and then rebase the feature branch onto master. We don't, but you could plausibly do reviews directly in git via editing the file with any comments.
One caution I have is that long term you should consider moving away from the gitlab tools if they are unable to fix accessibility concerns, so that everyone is on equal ground.
I also don't know how flexible he is on which browser or operating system he uses; he may want to try some others to see if they work any better.
I've been wanting to try gerrit however: https://gerrit-review.googlesource.com/Documentation/dev-des...
Please report back on whatever you end up doing.
One caution I have is that long term you should consider moving away from the gitlab tools if they are unable to fix accessibility concerns, so that everyone is on equal ground.
I also don't know how flexible he is on which browser or operating system he uses; he may want to try some others to see if they work any better.