Something that worked for me is that I have a profile where I am a domain expert who is reasonnably good at data science and software development. I am no rock star in any of the three fields, but this particular combination is pretty rare. I got my last 2 jobs this way: most applications just got lost, or ended in a meh screening interview, but there was this one job posting in the year that required this mix of skills, and I was just the obvious choice and got hired pretty much without competition.

I am not suggesting that you start a PhD in some obscure domain, but any additional skill can help stand appart from all other generalist front end developers. For instance in my last company we did quite a lot with geographical data, and if a front end dev showed even just the slightest knowledge of geodata (like knowing what a map projection is, or a knowledge of the technologies used to display maps efficiently on the web), he would quickly go on top of the pile. So if the is any domain where you know just a bit more than the average guy, even just as a hobby, I would say that it makes sense to display it on your CV and search for postings that might be related.