Maybe you can add new casino website I saw today in forum Getsats.club.
This is their forum topic:
https://bitcointalksearch.org/topic/--5489513
I know another gambling website from forum that is working on adding Lightning payments:
https://bitcointalksearch.org/topic/l0tt0com-5457016
Have you tried using the lightning network? I have been hearing that for a long time, but I have never tried to use the lightning address, to be honest. I don't know if I'm just confused or if I just don't understand right now.
So I'm just paying attention now. I rarely see gambling that has lightning payment options in that regard, maybe because there are many people like me who are confused or haven't tried using the lightning network yet.
I am quite in a similar position like yours, I have also heard about the lightning network and the advantages it offers to people who wants to save in commissions and seek for high speed in their transactions. However, I have not taken my time to learn about it enough for me to use it.
I may try, since exchanges (like Binance) are already giving support to that second layer solutions.
I know how to use an application to receive satoshis, but I don't have any idea how one is supposed to convert or send satoshis in the lightning network back to the main Blockchain of BTC.
By the way, besides of the relatively small number of people into this solution (as you mentioned) the lack of implementation may also have something to do with chain analysis. It is harder to track transactions in second layers.