Suggestion Pokemon let's go speed up mod ?

Consider that the games already do not run that great. Simply increasing the overall game speed similar to how you would in an emulator would require too much additional power, because everything has to go faster, that includes loading/data processing every time you touch a button. You can increase the walk/run speed, you can increase the speed of text messages, but you can't increase the speed of the actual loading and data processing going on that is likely much of the cause for why the Switch Pokemon games feel so sluggish/slow. You can speed up battles somewhat by disabling animations, increase the text message speed, but otherwise there is probably not much you can do to speed up battles. You can certainly have 2 or more walk/run speed and be able to get through the game a lot faster that way though but it won't fix how sluggish the games are, they're just poorly optimized and each new generation of Pokemon games seems to be more and more sluggish and unresponsive.
Short answer: Not possible, it would be too demanding
Slightly less short answer: You can disable battle animations, increase message speed and increase walk/run speed and maybe speed up transitions (in theory) but it is nowhere close to being the same thing as an overall 2x increase in game speed, but it's the best you can hope for on real hardware.

 

This is if you will pass more loops. It's possible to speed up things just by finding coefficients. This way it will have the same loops, but every difference will be f.e. 2x bigger, so speed will be 2x faster. F.e. some games utilize systemtick for this like Fire Emblem.

Dunno what emulator uses though.

 

AFAIK that would only speed up some aspects of the game so it's still nowhere near a 2x overall speed. You can speed up animations and transitions that way though.