OLED

An organic light-emitting diode (OLED or organic LED), also known as organic electroluminescent (organic EL) diode, is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound that emits light in response to an electric current. This organic layer is situated between two electrodes; typically, at least one of these electrodes is transparent. OLEDs are used to create digital displays in devices such as television screens, computer monitors, and portable systems such as smartphones and handheld game consoles. A major area of research is the development of white OLED devices for use in solid-state lighting applications.

Burn-in
Burn-in is possible with OLED, but not likely with normal use. Most "burn-in" is actually image retention, which goes away after a few minutes. You'll almost certainly see image retention long before it becomes permanent burn-in. Generally speaking, burn-in is something to be aware of, but not worry about.

This isn't a permanent problem but you may notice it once in a while. It's likely that it'll go away on its own rather than turn into permanent burn-in. Fortunately, there are plenty of ways to fix this and to avoid image retention or the risk of burn-in in future too.

Devices that work on OLED TVs
All current consoles like PS5, all Roku models (except the Roku SE which has AV video output), Blu-ray players, etc. can work perfectly with an OLED TV since they all have HDMI.

However, as for some old consoles like Wii, TV decoders or old DVD players, which only have AV video output, it is impossible to use them on OLED TV as they don't have AV video output like Plasma ones. . It makes it difficult to use them there, although you can with AV to HDMI converters, they may not look good forced to 4K, since such devices are not designed for 4K or 8K resolutions.