It is an interesting noise, maybe from the pump pulley but if true, the question is what would make it struggle at full turns. May try some bearing grease right on the steering stoppers where they have wear - and maybe swap them (between the wheels) if too much wear.
I don't think that pulley play is an issue per se. I can even leak a little without problems.
May use something like this (with care)
https://www.youtube.com/watch?v=qVWY2fMzrpc