Did a quick search and didn’t see anyone else post this. To get 4K 60 FPS output while docked for Hades 2 on the Switch 2, disabling “120 Hz Output” in Switch 2 System Settings > Display is required. Just choosing 4K TV resolution is not enough.

IMO, since the 4K seems to be upscaled, it’s not really enough of an image quality improvement to be worth it. But you could test for yourself.