KaiOS and Tizen also have a userbase wide enough to be considered major consumer OS's (even if primarily targeting markets such as India).
The Switch OS could probably also be considered major at this point with the number of devices out in the wild. Same goes for LGs WebOS. VxWorks is also fairly big, although at least Canon changed over to something custom for their cameras.
And that's just the consumer facing OSs. There's a lot of surprising ones, like Apples use of NetBSD for their Airport devices.
OS diversity is high outside common desktops, and desktops are a vanishingly small portion of consumer computers.
The Switch OS could probably also be considered major at this point with the number of devices out in the wild. Same goes for LGs WebOS. VxWorks is also fairly big, although at least Canon changed over to something custom for their cameras.
And that's just the consumer facing OSs. There's a lot of surprising ones, like Apples use of NetBSD for their Airport devices.
OS diversity is high outside common desktops, and desktops are a vanishingly small portion of consumer computers.