The games that will play natively on the steam frame will have to support it on a game level, but for streaming it’s handled at the os level through “Foveated Streaming”. So the PC isn’t getting an fps boost from it but it does allow the latency to be very low through streaming.

I’m not sure that the eye tracking data will be passed through for foveated rendering from the PC side though I can’t imagine why it wouldn’t. In that case you get both render and streaming which would be incredible