Fly.io probably runs it on Kubernetes as well. It can be something in the middle, like RunPod. If you select 8 GPUs, you'll get a complete host for yourself. Though there is a lot of stuff lacking at RunPod too. But Fly.io... First of all, I've never heard about this one. Second, the variety of GPUs is lacking. There are only 3 types, and the L40S on Fly.io is 61.4% more expensive than on RunPod. So I would say it is about marketing, marketplace, long-term strategy, and pricing. But it seems at least they made themselves known to me (I bet there others which heard about them first time today too).