I tried adding a suggestion for Amazon Pay as an Xsolla alternative (as Amazon own Twitch). That was closed because Amazon Pay is available through Xsolla.
So I'll cut to the point: Xsolla is awful.
Let me bypass Xsolla. Amazon Pay would be great, but PayPal (like Twitch used to have in the good old days) would be perfectly acceptable.
I've been told by Twitch Support that this is already available in some regions, so should be straightforward to roll out more widely.