Can you get Among us on a MacBook?

For M1 Macs, it would be in the App Store

For the Intel based macs, the only way is by using an Emulator for the time being

This link will help you with install Among Us on your Mac.

https://www.sportskeeda.com/esports/how-play-among-us-mac-step-by-step-guide

I do need to say that it won’t be my responsibility if you do get any viruses on your computer.

Of course yes. You will need to pay for that

Yes you can, I believe it should be on the App Store or you could try sideloading it.