You definitely should pick it up, it's definitely worth it! If you want it physically, Amazon has the first issue for super cheap too, and the second one comes out Wednesday.
Yeah, that's one of the main reasons I started the Kane Chronicles, other than it also being a Riordan series. I really enjoyed the first book, but I just never got around to the other two despite owning them. Lol oops. That's also why I have yet to read the crossover stories, too.
I like the idea of the TV/animated universe being separate from the movieverse tbh. I feel like the shows would fall into the awkward place Agents of SHIELD is, where if it is connected to thr big films, none of the recognizable Big Bads will ever make an appearance as the villain of the season, just be hinted at or talked about but never seen. And seeing as how Flarrow already had big names like Ra's, Slade, Vandal Savage, etc. I desperately want it to stay separate so the shows can do their own thing. Incidentally, I want the Titans show to stay away from the Flarrowverse so it can do it's own thing too, although I'd love to see Supergirl be a part of the Flarrowverse (which would also mean Supes exists in the Flarrowverse).