There are only so many (legal) things one can do in a casino to get an advantage, and I think most of them are well known.
There's a HUGE difference between "most of them" and "all of them." Many smart players spend a lot of their efforts trying to exploit that difference. Your term "(legal)" isn't black and white. By a long shot.
I'm not a table game player. But sometimes after taping a show, Richard and I will go out for a meal or drink with our guest. Just by sitting there with my mouth shut and listening, I'll sometimes hear Richard and the guest talk about a feature of a play that I certainly had not heard of before --- and sometimes wasn't on the list provided at the start of this thread. Obviously, if I want to keep Richard as a co-host (and I very much want to do that), I can't be blabbing those techniques around.
Even with items on the list (like counting side bets), it's often not clear how to do that. There are some very gifted computer guys trying to work out what the best count is for various new games --- combining accuracy and simplicity. Just knowing that a game is potentially countable is a whole lot different than actually having a count that works.
and there is the whole area of "getting away with it." In his "Beyond Numbers" blog James has been sharing some of his "how we do it" techniques. Depending on how knowledgeable you are, some of what he writes is common sense and some is eye opening. Were I a table games player, I'd devour his words over and over again. Many of the best APs consider James Grosjean the GOAT.
(And yes we've tried to get James on the show several times. He and Richard are good friends, and if Richard can't make it happen, it can't be done. But we'll keep trying.)