Hey @guaip,
I somehow missed that part about you knowing Javascript, my apologies.
But just by the fact that you know Javascript, then I believe you are much better off skills wise than you think are. Typescript can be learned in a day or a week, it’s just Javascript with types.
Now to your questions:
I guess spending so much time and energy in a framework, which is not even a proper language, feels wrong for an old schooler like me (especially Javascript). But I guess it’s what people want now.
There is nothing wrong with this. You want money and they want skills, it’s an exchange of value. You can’t outrun, outthink or out compete the market unless you want to starve to death.
I’m going to increase my search for agencies that still need a “visual” front-end guy to make some more money while I study the new stuff and look for a job.
Atta-boy! That’s the spirit. Learn and earn.
I’m curious if you found yourself in a similar situation before. If so, when did you decide to learn the new stuff? Any tips to share?
I spent 5 years dodging Javascript, and refused to learn React JS when it came out, choosing instead Ember JS. Wrong decision! I lost cash and opportunities by being blind and stupid. As the web got more and interactive and people started asking me to move away from static websites, I finally realised it was time to learn this stuff or end up a Luddite.
The best tip is this: don’t be a dinosaur(can’t recall where I read it) but you can’t be static. Always evolve. Yesterday was React, some time back it was crypto and today it’s AI, who knows what’s next. If you don’t change your approach and adapt to new stuff you’ll be left behind.
As for learning React: you’ll have to slug it out. Some of the things in React will make you want to scream, if you were a puritan like me: mixing CSS and JS will make you want to puke i.e. separation of concerns but after a while you’ll get used to it. So start and keep pushing, there is no other option, secret or formula. This is what the market wants and since you want/need the money, you need to comply.
Most importantly: don’t make bets. I bet on Ember JS and it ended up badly for me. Ember has a long learning curve, it has its own ecosystem of addons, which add more complexity to packaing since we already have node packages and is generally hard to when working with a backend API. I dropped it in 2017, but this was after spending time and money on books courses and plenty of code. And yet during that time, React was still there waiting for me 
Any idea on how hard can it be for a guy like me (average to good javascript, strong CSS/SASS, also PHP developer) to learn React and all the stuff that usually comes with it?
It’s not hard. Your knowledge of JS has already set you up for half the journey. The rest is knowledge and practice, and this coming from a guy who’s still coming to terms with React. Just slug it out. You can do it. And since frontend is your thing, once you get the hang of it, you’ll love it.
Conclusion:
@guaip save yourself the time and effort and do what the market needs and wants. After you have saved money then you can go around and play with shiny new toys. But if you blindly follow the advice of someone living in a country with a good welfare system then you’ll end up suffering for nothing.
Learn React. Learn it good and start applying to frontend jobs.
I wish you the best.