I've tried online courses (Chessable, Chessly) and books and all were generally an expensive waste of time when trying to learn openings.

The problem was that I was trying to memorize lines instead of, you know, actually play chess. Chess is hard and I find 90% of the time my subconscious is trying to protect itself by playing chess without actually playing it. A classic example was thinking the London or other set up openings were a good idea to "minimize learning theory".

Fact is, though, at some point you are out of book and staring at a position you don't understand and have no idea what to do.

What finally helped me was finding Chessbrah (I will sound like a paid shill because I love Chessbrah but you'll have to trust me that, while undoubtly a shill, I'm certainly not being paid).

GM Aman Hambleton is famous for his "Habits" series targeting beginners looking to get started playing blitz and bullet but did you know he does several opening themed speedruns? He will take an account from below 1000 (typically 400 or 800) and play an opening (sometimes the same as white and black, sometimes playing one specific opening as white and another with black) every game--even forcing it--and take the account up to the 2400 level, on chesscom.

Here are my favorite runs of his, although he has done many more:

• Stonewall Speedrun
• French Defense Speedrun
• Queen's Gambit Speedrun
• Taimanov Sicilian Speedrun
• Orangutan Speedrun

The key is that you are seeing the opening played at a relatable level, and that Aman focusses on ideas, the set up you'd like, the attacking ideas, the defensive resources, the key pawn breaks, the things not to do, and, as a bonus, throws in middle and end game tips that tend to be both fundamental and instructive. He repeats key points again and again and again so they tend to stick, and you learn ideas instead of relying on memorizing sequences of moves.

For those interested, I put together some guides and PGN collections for several of the chessbrah openings and publish them on my Github

The guides are AI generated but I checked them and they were largely sound, imo.
The PGNs are annotated by me (or else unannotated) with links to the YouTube videos added by AI.

Interestingly, these days I'm typically just playing e4/e5 and trying to play chess from move 2. Maybe it's just me, but I found that trying to force set ups or being too focussed on set ups led me to auto pilot the first several moves a bit, even to the point I'd often miss hanging pieces in the first few moves. But it's nice to be able to throw in the odd 1. b4 or 1... c5 or 1. d4 or 1... e6 to mix it up now and again and keep the games fresh. Anyway, I hope someone can get something out of these resources.