@Eric Zhang i found that they do have support for it — I see this on the 15 Pro’s tech specs page:

> Video mirroring and video out support: Up to 4K HDR through native DisplayPort output over USB-C or USB-C Digital AV Adapter (model A2119; adapter sold separately)

https://www.apple.com/iphone-15-pro/specs/

No idea if there is latency like the Lightning video output has, though.