TLDR; 1 year old male cat is a picky eater and need some recommendations/tips and tricks on what else I can do to keep him hydrated

My 1 year old grey boy won’t eat fancy feast anymore, I’ve tried churu’s wet foods and the Sheba pate that he’ll sniff and lick but won’t finish his plate. He also drinks water by dipping his paw in the bowls a lot and licking it off, I haven’t seen him drink from any of the fountains. Wetting the dry doesn’t work and he doesn’t like toppers. But he does like the Churu tubes. I’m just concerned about his hydration. I’ve already had to run him to the emergency vet because of constipation. I’ve had him on hairball control dry since then, he likes that. I had hoped the extra fiber would prevent anymore blockage. He’s got a vet appointment soon but in the meantime if anyone has any advice I’m willing to try anything!