Mostly a non issue in my view.
Yes, OLED are technically more ‘susceptible’ than LCD or QLED, but since your focus is gaming, the images will be refreshing frequently.
Burn-in is really about static images, so stuff like watermarks for example. Don’t leave your TV on all day if you’re not using it. Simple.
But here’s the thing: if you have even a small emerging issue, you’ll see image retention well before it becomes permanent - and that is fixed by turning off the screen for a few minutes (which might be a sign it’s time to take a break anyway
).
My view is that it’s possible but unlikely and I wouldn’t let it stop me from buying OLED if it ticks all other boxes. Good luck haggling!