Did some research and found PokerStars offering VR poker which might be the only other alternative in this case. There is very little demand currently for VR gambling since it's a niche and very few people would want to purchase a VR headset just for the sake of gambling.
However, I don't see why you are trying to find another VR headset that is Oculus Quest 2 goggles has the highest resolution among others, it's 1,832 by 1,920 (per eye) compared to Playstation4 and steamVR.
You misunderstood him. He meant to say that slotsmillion supports Oculus rift, but not quest 2 which is his headset.