I wouldn't consider myself to have good dexterity at all but have been able to play fighting games and work my way up the ranked ladder. I'd say if Tekken 8 looks cool, give it a try.

The main problem with Tekken is that it doesn't really document its systems with tutorials or a manual. Fortunately, YouTube will teach you more than enough. Tekken also tends to reward legacy knowledge more than most fighting games, so you'll probably find that Tekken 7 tutorials get you farther than you expect.

Tekken 8 just released a free demo on PS5 (comes out on other platforms in a week). Try it out. You might end up liking the game.

Dexterity is not the issue. For Tekken it’s just knowledge and experience. There’s a ton to learn and practice. It’s huge. Much higher than stuff like street fighter. And I’m not talking about fancy tech. I mean the basic controls and move lists. You will not likely get to a point where you know everyone’s moves.

The reason to play fighting games is strictly that you like the idea of honing the skill and playing competitive 1v1 matches to improve. Progression and reward is pretty different from other genres in this sense.