Where can one learn about these? Resources on fast moving areas like this is super hard to find if you're not "in the know" already.
The game these days is all about reverse engineering strategy principles from GTO simulation output. E.g. what general principle causes the solver output to say raise 30% in this spot vs raise 80%? If you come up with a coherent story, you can apply that thought process to new situations. It's a totally different game than it was a decade ago
Here is one of the solvers if you are interested: https://piosolver.myshopify.com/
Fwiw there is a significant amount of skill involved in choosing how to run simulations. I think they have some intro videos to help you
and sometimes a pretty significant amount of memory - these applications use massive amounts of it
Anyway, it's still not best to play like a robot in live low stakes games, which are probably what you're going to be playing. Exploit the shit out of your opponents. GTO has some good concepts that are easy to implement, but I'd work on studying your opponents and the mistakes they are making, and decide how to capitalize on those mistakes.
If you are going to multi-table online, ignore everything I just said and become best friends with some solver software.
Good luck.
Piosolver has several features that lets you emulate how your opponent plays, such as "node locking", that "lock" the game tree node to the strategy you suspect your opponent plays, and shows you how to maximally exploit it.
Otherwise, what is your exploitation based on? Certainly some people have great instincts for the game, but it's just untrue that solvers can't help you exploit weaker players. For example, if you're on a given board and a given river and an opponent makes a big bet, if your opponent bluffs too much you should call, if they don't bluff enough you should fold. But the solver teaches you how often they should be bluffing and thus what "too much" or "not enough" even means.
This is why I prefer the term "theory-based" to GTO, since the point of studying GTO is not to play GTO but to develop a better understanding of the underlying mechanics of the game.
I think GTO is a great way to think about the game. I don't think studying solvers is important to understand the game well, or GTO. When solvers provide an insight, it generally trickles out to the poker community and we all hear about it. It's much easier to digest traditional educational content than to futz around with a solver, and a much better use of time for a new player.