They basically did similar stuff with some of the stuff in the sm3d collection thingy.
They did not.
For Super Mario 64, they emulated it. They increased the resolution the game renders at (trivial with emulation of 3D systems) and they used basic LUA patches in the emulator to override HUD textures with higher resolution ones adjusted for the Switch controller.
They did not add any further enhancements in any way. Compared to even 64 DS, it was extremely sophomoric. Compared to the Super Mario 64 decomp project, and what its native switch port is capable of (more on that later), it’s an incredibly lazy port. They didn’t even fix the slowdown with Bowser’s Sub that is as simple as adjusting a single compiler flag when you build the ROM from the N64 game source code.
For Sunshine, it’s an admittedly impressive solution of mostly emulation with some sections of the game engine ported (I think it’s the audio processing?). Once again, the game is rendered at a higher resolution, but they did not redo ot improve further any textures (besides some of the HUD again), graphical effects, or game content. Wind Waker HD this ain’t.
For Galaxy they cannibalized the existing port of it to Android on the NVidia Shield. The Switch shares most of the important internals with it (CPU, GPU). It’s a combo of emulation with certain key code ported, like Sunshine. Again, besides resolution and HUD, no improvements.
Beyond that, Nintendo has been content to sell straight up emulation through the Virtual Console service since the Wii. They’ve had multiple instances of straight ports over the years, and some of the most popular Switch games are straight ports with DLC bundled in.
There are numerous impressive remakes they have done over the years, but that is absolutely not the norm.
The Super Mario 64 decomp on the Switch supports (not available in Nintendo’s official port in 3D All Stars):
Effectively infinite render distance for objects (coins, enemies, stars, etc)
60 fps (compared to the original/all stars 30fps at best)
True analog camera control using the right stick (All Stars is just the original’s clunky button based control mapped to the stick)
All sorts of QoL options like collecting stars not kicking you out of a level, options for streamlined/faster message boxes
Optional bugfixes
Optional cheats
Variety of HD texture packs to choose from
Variety of higher quality 3D model packs to choose from
Support for an astounding variety of mods. Levels, entire new games, new characters, new movement and control options (Odyssey Mario in 64 with full cappy and enemy capture mechanics anyone?)
Support for many more languages
Nearly all of the above is toggleable mid-game from the pause menu.
I don’t think anyone was expecting something amazing out of 3D All Stars, but they absolutely fucking phoned it in.