I'm happy to be proven wrong, but the lack of replies seems quite telling. From all of my research I have come to believe that this is because self-custody lightning is horrendously time consuming and expensive. My understanding is that the amount of money you have to put up up front in order to be able to properly get started opening channels with a self-custody lightning node is definitely a substantial limiting factor, and while it's possible to start a lightning node with less up front, it can increase the difficulty exponentially.