This - over specialism is career suicide. Most places I've worked have a maximum of three tiers of skillset in their mix, namely devops to handle CI, prod, etc back end devs for caring about API side stuff, and frontend for giving a damn about the users.

I realise this sounds basic, but that's the point: almost all of those things are everywhere. Bury yourself in a tiny slice of one of those things and you've become un-or-over qualified for most of the market.