Is there an advantage to playing on Linux over Windows?

Yes, 1.001 Linux has much better input handling and also for Neutral and True Pacifist it has Mad Dummy Skip, which can't be done on any Windows version and saves over a minute and a half.

And on Linux, you can do sgs (sea grass skip) which save a decent amount of time too.

You can do SGS on all versions

Do I have to play on the Linux operating system to use the Linux version?

No, you don't. You'll be able to find a Linux on windows patch at https://www.speedrun.com/undertale/resources (posted by OceanBagel. Just scroll down patches and it should be there. This guide by Shayy is also really helpful https://www.speedrun.com/undertale/guide/exjem .

can you do sgs on windows?? lol I didn't know~ feel free to correct me if I got anything wrong~

sgs isnt a version specific skip like mad dummy skip, and it is only marginally affected by the unoptimal input handling of japenese versions. IE, doing stick sgs requires perfect execution with 0 frames to spare and cell phone sgs isnt actually too bad but is a frame more precise than windows/linux assuming you hit the first action key and release it a frame after.

i love speedrun

@Bain8renn that is for JP, you can do inputs on consecutive frames on 1.0-1.001 windows but you have to release the first input before the start of the second frame

Nvm I’m stupid lol thought you were talking about windows still lol

lol