How do they get to 108MP?
By having a 108 megapixel sensor. They don't care if it gets better results or not, that's only required in the pro market where photographers don't care about specs but only about results.
Selling phones has been about specs for years - variously fighting over not just camera megapixels but also screen size, display pixels, battery size, number of cores, screen to body ratio, number of cameras... Megapixels has been forgotten the last couple years in the "number of cameras" wars, but it looks megapixels is making a comeback.