I kinda prefer the low-res N64 look for this game. Bumping the resolution so high only shows how poor the texturing and even the modeling is. This is not Banjo-Kazooie.
It also looks like they tried to upscale the textures using AI? Dunno, that's the impression i get because the textures look a bit messy.
The softness of the original could be emulated even at higher-resolutions if they used decent emulation, like how Parallel RDP can emulate all N64 filters. This one looks as sharp as a PC game though. To be fair, Parallel RDP is a demanding solution that the Switch probably couldn't handle.
IMO, they should have kept a lower resolution (480p at most) and maybe an optional CRT shader (a proper one, not just a bunch of horizontal lines over the picture) to make it look good enough on high-res displays. The frame rate update is always a good thing as well.