Basically One Punch Man, except without satire and more about the psychological drama of being so strong that you can't form connections with people.
Probably fantasy or isekai. Guy gets his powers when he's a kid, high-fives his friend into a thin red paste. Can't contain his power without releasing occasional bursts that destroy everything around him. Is contracted by different nations to help in wars and lives a lonely lifestyle. Then he gets friends or whatever and it turns out the bursts of power are tied to his psyche and get better when he's more calm.
The fights are still hard because he has to worry about collateral and will mostly fight crazy lunatics who don't care about death.
Lots of character death. It's like torturing a guy who's too strong to even kill himself, but also with some inspirational messaging.
This could be a two-pronged attack since the character could become popular by being "le most powerful shonen character soloing all the verses" to draw people in, and then good writing/psycho drama to keep them engaged.
Really, this seems like a pretty marketable idea, the problem is making it not slop. Saitama works well when subverting the idea of being powerful in a comedic sense, so I thought this could also work if it subverted that in a different way.