I ask before I take the interview. Location, salary range, linux laptop are prerequisites to me working for anyone. If they punt on the laptop question it means no and they are hoping you’ll want the job even without. I can promise you I won’t, and if you view that as a red flag I can promise I don’t want to work there so I don’t care.
If its a hard requirement for you just say that and say that’s for workflow and you don’t want to waste anyone’s time
What if you aren’t flexible? I never couch, I just say in use Linux for my workflow, can you accommodate that?