It's a normal thing to ask in an interview, I ask the same every time, so far I've always gotten one, after all most things I work with require Windows machine to have WSL anyways, so might as well cut one layer.

That being said it all comes down to how you ask it and how valuable you are, if a junior said "I only work with Linux, either you give me a Linux box or I won't take the job" you might be cut from the race by HR before any person who even understands what you're asking gets to see you because you're being inflexible. If on the other hand you're a senior and go through the interview and at the end when you get to the questions ask what's the policy for OS on work machines, you're much more likely to get the answer you're looking for. That is unless you're working for a Windows specific program, which obviously will need a Windows box, and not many companies are willing to give you two PCs.