rejected after the final round with feedback that just said 'went with another candidate' and I'm trying not to read into it

No specifics, no 'work on X', nothing. Part of me wants to assume it was close and part of me wants to assume I bombed something I didn't even notice. Probably neither is useful to dwell on. Applying to the next thing today instead of trying to reverse engineer a decision I'll never get real information about.