The way I've always seen and understood it is that there's two types of companies :

- starting businesses/(relatively) small businesses that look for someone with the broadest skills possible, this way you employ fewer people to get the job done and have a MVP

- established/historical/corporate companies that already have an established stack that you are not going to reinvent (because of the scale or simply because they wont even let you try) and these companies tend to know exactly what their weaknesses are and they search for way more specialized people to fill those gaps. they also look for "fullstack" devs but way more skilleld, akin to "tech gurus" that act more as lead devs/team supervisors to help out anyone that might run into trouble, so in this case you'd better have some nice work experience.

Anyways, frontend/backend/fullstack, in the end, the pay potential and employability is all about how you sell yourself and nothing more.