They can do all of that without having to cut the game's framerate.
Majora's Mask 3D and Ocarina of Time 3D are full graphics remake, and they ran better than the originals.
I don't see how much they'd have to change the game in order for it to get to a level it's more demanding than Switch games like Super Mario Odyssey while being in its core, skeleton, engine and world building a Game Cube maze based game.
It is true for games built from the ground up for Switch(like Astral Chain looking better than Bayonetta 3, or Luigi's Mansion 3 looking better than Super Mario Odyssey) but I can't see a level of enhancement they'd get to a point they'd need to cut the framerate by half to achieve.
I mean, Super Mario Odyssey is the most ambitious world map wise a game can get without being full open world, has all modern technical graphical features, features a great geometry (Mario could be better tho), lighting and everything, and is still 60FPS.
They absolutely can put high quality textures, make very rounded models, make a new lighting engine and everything else you'd expect from a full asset remake, without needing to cut the framerate by half. For the game to reach a level of ambition it can't be running at 60FPS it would mean an actual reimagining like Samus Returns or Link's Awakening, not a 1:1 remake using the same skeleton. Like, making the environments bigger or whatever.
Everything else they can possibly do was already done at least once by a 60FPS Switch game, be it Super Mario Odyssey, Splatoon 3, Mario Kart 8 Deluxe, Super Smash Bros. Ultimate and so on.