Unavoidably, but is "becoming a manager" the only definition of "moving up?"

Not at an employer you want to be at long term.

Unfortunately, the answer is "yes." I have avoided doing that and the only way I moved "up" was first to move around, then to move into a consulting firm, then finally to my own corporation that is also a consulting firm. Is that a viable career trajectory? I have made it work, but I long ago gave up the idea that I would be anything except an "independent contributor." I did look at jobs like "architect" but those jobs are holding pens for people who couldn't cut it as developers but had enough company knowledge to want to keep around. I don't know what most architects do all day, I've never had one actually help accomplish anything. They like meetings and conferences and overeating, it seems.

Tech is a badly broken field in terms of career advancement. For a long time it made me very jaded. But I'm rich now, so I could give a shit.

Maintaining contact with tech (as in engineering) may not be the success criterion.