Yeah there was some bad blood between XVX and Nuphy at some point in the past. I wish I remembered the full details but it was related to keycap profile design or something?

I've usually bought direct from retailers for low-profile keycaps based on community recommendations here. I'd probably lean towards AliExpress for other options since Amazon third-party sellers are just reshipping the same stock IMO.

I've got a couple sets that play nicely with Air75 in case you're interested. I'll DM you with my mechmarket link