For a past python developer, trying out something like Django a bit with converting a past project would be less work than react for a js developer and probably a good refresher.
But, if Facebook actually hires react engineers everywhere and just doesn't like their own job platform, then they probably hire php engineers everywhere as php is the platform they are the most famous for sinking money into modernizing.. So again, I'm left to wonder why anyone who already knows php would be told to learn react before looking for a job.
It's a lot like always being told to learn Ruby on Rails a few years back even if you knew nothing at all about ruby. I wonder where all those ruby illiterate RoR engineers ended up.
Granted, I don't know your market, but if it's outside the typical 5-10 cities, that might be the problem.
Ok, so let's assume Facebook is hiring today and for the last 5 years in 10 job markets.
Damn hard to find a company actually using it in many markets for most of that time.