My wife uses Arch (actually). She calls it the internet, when she really means Facebook. She knows it isn't Apple but it gets a bit vague after that!
The last time I had to fire up the Mesh Central client to sort something out on her desktop from work was around three months ago. Every couple of weeks I ssh into it, update it and schedule a reboot for 03:00.
If the client is blocking OS fingerprinting by returning generic navigator.appVersion and userAgent values you should probably just assume Linux in the first place.