Search the texture in the materials tab with the Extended Spawnmenu, then apply the textures with either the default Material Tool or Sub Material Tool.

how do you put on the textures

How Source engine works is that every prop only has a single "slot" for the skins, and the main one already used it on the screens, and you can't really change both controllers separately on the stand or controller ones, since you can only assign changing a single texture for the "slot".

And if it became a bodygroup, you would need to have another controller model to replace the old one just for the textures, same to another controller, which will cause unnecessary performance issue, or else the textures will overlap each other and flickering.

And fixing both of those issues would not be as simple as just let you replace the texture manually with SubMaterial Tool.

So yeah, it's just because of the limitation of Source, oof.

Why not just make it into a skin or a bodygroup? Cause I dont know where it is

Ahh I see.
Well they're there anyways.

Oh, I didnt remember seeing that in the description

Oh those are already packed in the original Nintendo Switch model lol, you just need to manually replace the textures since they're not set as alternative skins already.

Will we eventually get the red and blue?