Maybe infosec or cyber security would be similar? I'm a fullstack turned mostly FE developer these days, but I'm very interested in security and it seems like there is a lot of demand out there for that skill set and plenty of opportunity. It seems like it would push a lot of the same buttons that you mentioned (fixing broken systems, lots of autonomy, working with smart folks). I tend to get bored with long-term projects unless there are still interesting problems to be solved so working on lots of smaller projects sounds pretty appealing, and there's seemingly no end to new systems/devices/websites that are just riddled with holes. Seems like a perfect role and potentially more lucrative than IT (although this is just pure guessing, I haven't compared numbers).