They're generally legitimate, particularly the ones listed on Wizard of Odds and similar legitimate gaming sites.
The better question is what are you going to do there? The days of the bonus bonanza are all but gone, most are now unplayable. The poker games I suspect are corrupt, with multiple players sharing downcard information at a table.
Live dealer casinos are now common but there are only two studios making their games available to US players. They both have 50% pen at best. You have the advantage that you can use software to assist you (to cheat, let's not obfuscate) but that will only provide you with minimal help. You can attempt to use a combination of false ID, cryptocurrency, and a VPN to represent yourself as a non-American and there are better conditions available for the live dealer casinos that accept only non-US players, but that is hairy and I cannot guarantee you will get paid if your act isn't good enough. Perhaps if you have a partner in an online casino-friendly jurisdiction, he can represent the partnership when dealing with the business end of the casino while you play over a VPN pointing to his country.
Before you do any of that go and watch the live dealer games, decide what you want to play, what it will take to beat it and for how much.