Not a fan of Facebook or React (though React Native is IMHO the one eyed among the blind for cross platform mobile development), but I think that's a bit far fetched. I do think Facebook has (or had?) genuinely an engineering culture that wants to give something back.
This is true. I've been to several conferences where FB sent engineers to talk about their open source projects or how they used a particular language or framework.
I remember the conflicted feeling of strongly disliking their products and leadership but liking their contributions. Same energy but more intense in both directions many years later.
From my personal experience, yes, but your mileage may vary. I tried to like Flutter multiple times, but can't. Capacitator etc feel fairly hacky. All the other options are comparatively obscure.
It helps that I like React alright. I don't think it's particularly well designed or enjoyable to use, and I hate debugging React code, but it's manageable with good development practices. Same goes for JS/TS. Not great, not terrible.
