Genuine question: is it actually reasonable to compare desktop/laptop OS market share with handheld market share? Like... what does that actually tell us? I suppose in the case of gaming it can be useful, since at this point more games are played on Linux (due to SteamDeck) than on macOS. But otherwise, I always get a weird feeling when someone lumps these stats together.
I guess part of the weirdness I feel is when people say "Linux is the most used OS in the world" because of all the Android devices floating around, which is super misleading, since "Linux" isn't really an OS on its own anymore. (Technically it never was, but I'm not one of the "GNU/Linux" pedants, so...) Android and GNU/Linux are very distinct, very different OSes, so it makes no sense to lump them together. "Linux is the most-used kernel in the world" is a more accurate statement, but, again, I'm not really sure what that actually tells us in practical terms.
I think it is actually a reasonable thing to compare. I've had similar thoughts on the Android comparison. Yes, Linux is the most widely used kernel in the world, but that doesn't mean that desktop GNU/Linux is up to the same level of usability. That doesn't mean that desktop GNU/Linux would provide a good touchscreen experience on a tablet. It could, but the entire userspace software stack is completely different.
I think what it does indicate is that the kernel is featureful, stable, extensible, reliable, and a good base to build products and services from.
SteamOS on the Steam Deck is a close cousin of desktop GNU/Linux, purpose built for gaming. It might be a handheld, but it's also a PC. I think the popularity of the device tells us that the compatibility of Linux with Windows software, games especially, is good enough for the average person. It tells us that people are willing to tolerate a bit of a learning curve and some differences to what they're accustomed to so long as the value is there, and 95% of things just work.
It's also worth noting that many Steam Deck users choose to continue using SteamOS, based on Linux, to run their Windows games, in spite of the fact that their device will also run Windows.
In this case it seems fine, as SteamDeck is not very distinct from a regular PC and SteamOS is really just a Linux distribution. Anything compatible with SteamDeck can be ran on other Linux installations, as well as other form factors.
I guess part of the weirdness I feel is when people say "Linux is the most used OS in the world" because of all the Android devices floating around, which is super misleading, since "Linux" isn't really an OS on its own anymore. (Technically it never was, but I'm not one of the "GNU/Linux" pedants, so...) Android and GNU/Linux are very distinct, very different OSes, so it makes no sense to lump them together. "Linux is the most-used kernel in the world" is a more accurate statement, but, again, I'm not really sure what that actually tells us in practical terms.