There isn't a shortage of generic developers, but there are shortages of specialized developers. One shortage example would be an SRE who knows Azure, Kubernete

There isn't a shortage of generic developers, but there are shortages of specialized developers. One shortage example would be an SRE who knows Azure, Kubernetes, Jenkins, and Jira, very well. Another example would be a front-end developer who knows iOS development so well that they can make up for the pit-falls of React Native while also writing half decent typescript code. It's often difficult to interview specialized developers because the specialist often understands (or pretends to understand) the specialty better then the interviewer themselves. These hiring opportunities represent a large number (maybe even a majority) of roles at small, medium, and large, companies. FANNG and maybe a few other companies which have custom tool chains from top to bottom are a little bit different because Google probably doesn't care if you know Jenkins because you'll have to be trained in their homegrown alternative anyways.