Yeah but you have to remember the sun is on the other side of the earth so be careful looking down

They work at night, you just have to wear them backwards

They only work if you're looking in the direction of the sun, so make sure you stare at the right part of the ground

Colanders and looking at the ground work quite well during the day. It is like having 100s of pin hole cameras. I haven't tested them at night, but it can't hurt to pack one.

Source: My astronomer boss and using them for the last ecilpse

The ones running Linux are fine. I wouldn't trust the eclipse glasses from Apple or Microsoft, since they're closed source.