Gordon would've been a great signing a season or two ago but we've outgrown him in my opinion. I don't see what he does that's better than Martinelli. Both are fast wingers who work extremely hard out of possession, are good finishers and flawed 1v1 players. Personally, I'd just keep Martinelli and look to add a different option to him so we can rotate both of them, along with Eze. The one think I'd be looking to add is elite 1v1 ability.
I'd be very interested in: Morgan Rogers, Yan Diomande, Illiman Ndiaye, Jean-Matteo Bahoya probably in that order although Ndiaye is fast becoming someone I think would skyrocket in a proper team.