Desktop 3070 can be significantly faster than a mobile 3080. Mobile 3000 series performance depends a lot on the specific notebook though, as they have different power levels. But you shouldn’t worry about losing performance with the 3070.
https://technical.city/en/video/GeForce-RTX-3080-mobile-vs-GeForce-RTX-3070
The 5800X is also an upgrade from the mobile CPU.
https://www.cpu-monkey.com/en/compare_cpu-intel_core_i7_11800h-1959-vs-amd_ryzen_7_5800x-1747
You should have no issues at 1080p nor at 1440p.