Unless you plan on watching your footage on a large computer screen or TV monitor, resolution isn’t critically important.
You’re never going to try and capture a still image from your rolling action cam footage and attempt to print it to an A3-sized wall poster.
At best, you want to view your footage at 4K, but even that’s a bit much, as video recording technology leapfrogs ahead of screen capabilities.
However, resolution capabilities on MTB action cameras are getting more and more impressive. Many are now capable of recording in 4K and 60 frames per second, and the GoPro Hero9 and Hero10 Black go even higher.