I can assure you, we’re more than “single digits” as somebody said. 
I’ve just got Roon Core running and ARC working on my NixOS setup, beautiful. I have an AMD Ryzen 7 desktop workstation, Dell XPS laptop workstation, and a 10 y/o Mac. They all run Linux, currently on the desktop and listening; hence I must switch headphones to watch a YouTube video hehe.
The Mac is basically too old to do anything with. The XPS is a beast but runs the same build as the desktop (purely reproducible, identical builds are the point of using NixOS). So, I’ll probably try a VM when I get a chance, only need the Remote for the setup after all.
Also in the middle of settling on a smart home solution with smart speakers (with assistant) and I’m kinda stuck in the middle since I use iPhone and Apple Watch, whole family using Apple products, expensive as fak compared to Amazon but don’t want to say “Hey Siri, Alexa, bla bla” and use both. Messy. And I’m not getting rid of the watch, I love that thing. 
Guessing I’ll end up getting a HomePod for the best integration. Would be nice if they opened up a bit, I mean I can use Alexa from my Sennheiser bluetooth headphones but Siri seems locked to strictly Apple. It’s a comfy walled garden though, I don’t mind, but more interop as far as assistants and perhaps just using Matter/Thread instead of 20 different protocols.
Most users probably use Mac, and we may be a few that use Linux as daily driver. But just some CLI, web interface (definitely expected that), whatever, anything that can change the EQ or something at least, would be expected from such a premium service. Or an API—I’ll build my own app, np.
But, I learned long ago that if I choose to run this OS (especially a non-FHS distro), I will need to fix ■■■■ on my own and that we’re basically the lowest priority users in most client-side commercial software, usually for valid business reasons. Ubuntu and Pop! OS bring some mainstream folks though which is nice to see! 