> something to specialize and build complex products for
Generally you specialize in a particular business domain. Being realistic, you get this skill by repeating the above (PM and PR) in a particular domain enough that it soaks your brain like a brine. This is particularly true if you work in a regulated industry. If you wanted to get into a particular domain, target working for teams and companies explicitly working that domain as a way to immerse yourself. Once there, get cozy with the Product Manager as a way of drip-feeding learning the domain.
So I’d invest in optimizing my cv to pass as many hr filters as i can and in my portfolio of pet projects or open source contributions — to demonstrate that I am capable to do meaningful work e2e.