I was running MATE door years before switching to Windows 8.1 and shortly after first public beta of Windows 10 when it was available. I was even helping translating it to Polish for like a month or two, but given that I was probably like B1 (about B2 right now) in English at that time it was probably not ideal, lol.
I was that guy, but I gave up and just call it Linux, since there’s really no other name you can call it at that point. GNU/Linux is as correct as Systemd/Linux or Electron/Linux (for these quite a few VScode/Spotify/Discord/Other Electron app enjoyers).