Apple has included excellent display panels on iMacs for years, but for the longest time, there hasn’t really been a way to use it for anything other than macOS. There used to be a feature called Target Display Mode, but it’s long been discontinued. This has been a shame, since plenty of iMacs have excellent displays that go to waste after the compute is outdated.
I’ve found a pretty good solution though, and it involves a 4K capture card and one nifty app available on the Mac App Store. Any HDMI input, whether that be a Switch 2, PS5, Xbox, or something else – can display on your iMac (or USB-C iPad!)