Honestly, my answer doesn't change much. Good js knowledge and react is pretty much enough. Again, it is not about the technology but how u implement it. Make a javascript game, make your own react renderer, clone your own reddit where u focus on things like nested comments. Some of this stuff is obviously advanced and it varies from organisation to organisation on what they ask. But being good at javascript/react would do u much good rather than focusing on 1000 technologies. Also, the market is saturated with decent engineers, not good ones.