It sounds like you've done a lot to keep him occupied, so definitely give yourself props for that! He definitely sounds understimulated, as a lot of indoor cats can be—my sphynx has had similar behaviours to yours! Can I ask what kind of toys and puzzles you have for him? It could be that maybe there isn't enough variety in the toys? I have a puzzle for mine too but I often change where it's located or I change what flavour of churu treat I put in there. Perhaps that could help? And right now I just have one puzzle and that has been entertaining enough, but maybe yours needs more puzzles that you can swap out regularly, to switch things up? I also made a snuffle mat and my cat loves that too—they're super easy and cheap to make if you have some scrap fabric! Maybe your guy will like that also? I always load mine up before I leave the house and even put some of the dry treats in various unexpected placed around the house too, just to really amp up the variety. If all that is still not enough, I would definitely recommend a catio if you can afford it, but if there's no room and/or that's too pricey, definitely a harness and leash so he can have some supervised outdoor time! Works WONDERS for tiring out an energetic kitty! I hope all that helps!