To be seen as a "monopolist" under the law,
you must have "the long term ability to raise price or exclude competitors". Since Android itself is free and open source it can't really do either.
I didn't use the phrase "monopolist", I use the phrase "monopoly". Almost any non-Apple smartphone device runs a variant of Android, which is a monopoly. I point out that whilst AOSP is open source, much of what makes an Android phone an Android phone (Google Search, Google Chrome, YouTube, Play Store, Maps and more) does require a license from Google. Outside of China, there are very limited options that don't bundle Android with Google's services and even the Chinese phone manufacturers included it in their devices for international sales. Epic's case against Google actually demonstrates Google leveraging this to attempt to exclude Fortnite from OEM devices.
Android itself came seemingly out of nowhere, but it was being worked on back to 2003 or something like that before Google bought them. It's entirely possible that there's another OS being developed out there that will disrupt the current status quo. The fact that the AOSP source is free and open means aspiring OS developers get a head start.
My point is that it's existence as free and open in a sense hampers the commercial market because there is limited value in producing another operating system for profit. Android prior to Google acquiring it was not in a healthy place and had Google not saved it then I doubt they'd have gotten to market alone. Of course Google did acquire them and took steps to open it for free in the service of Google's services businesses.
I'm also not convinced that the reason Windows Mobile and WebOS went away were entirely because of Android. The hardware and software are not truly unrelated to each other-- a great OS on mediocre hardware will fail in the market, just as great hardware with a mediocre OS will.
I've pointed this one out elsewhere that Microsoft made a bunch of fatal missteps along the way with Windows on smartphones. The launch of Windows Phone 7 had significantly less features compared to Windows Phone 6.5, Windows Phone 8 was incompatible with all of the Windows Phone 7 devices. Microsoft didn't treat the threat of iPhone seriously and was slow to adapt then punished the consumers who used them. The phones weren't horrible devices, I spent some quality time with the Nokia Lumia however Microsoft had lost it's entire OEM market to Android almost immediately after Android is released.
WebOS was an interesting one but I think it came too late and HP weren't really able to make it a success in the time they gave it before deciding they wanted to move on. HP had a bunch of other issues at the time but I seem to recall they had a bunch of carrier orders for the WebOS phones that got cancelled once HP cooled. Similarly the Fire Phone never really took off in part because whilst it was Android based, stuff like the Maps API not working properly and it's own App Store really made it distinct enough to put up a barrier to entry (look up API redirection issues on Fire phone for examples of how it never quite worked identically).
That said almost everyone moved much quicker than RIM did with Blackberry who thought they were secure with their particular brand of enterprise lock in.
You might be able to make a case for separate hw/sw markets, but I think there's also the case that there's one market for mobile device systems. Are there any mobile platforms, such as the Intel PC platform, that allows you to install an OS of your choice? I'll admit to not being 'm pretty sure that when you chose a device, the HW and SW are a matched set. If they really can't be purchased independently, then they seem to be one market.
The consumers of the smartphone operating system market is generally the OEMs though and it's their move to from Windows over to Android that eliminated that market for Microsoft. I don't blame them because if you're focusing on differentiating on hardware as your primary driver however that leads to the pairing you talk about. It is also an interesting transition point because prior to the smartphone generation almost every hardware manufacturer had their own operating system to run their devices.
There have been a few projects in the Linux space over time, Nokia's Maemo devices like the N900 could be leveraged to install custom images. The OpenMoko project supported the Neo based devices like Freerunner in the 2000's but that died off around 2010/2011. Along the way folk have tried to put custom Linux distros on various Android devices with varying levels of success and more recently Pinephone are targeting the Linux distros as well. These devices in the smartphone market come and go but they have existed.
As someone who also has a foot in the Linux camp, I must admit I was excited by the prospect of Android bringing Linux to a more mainstream situation but I don't think it's ended up the way I know I'd expected.
I agree with most of your logic on the MS story, but I think you got this bit
backwards-- Microsoft had licensed Mosaic and was building IE for Win95 (32bit Windows) and had requested that Netscape avoid the Win95 market, and then backed that request with a threat.
Thanks for fixing that and that's good clarification of it being backwards. Fundamentally Microsoft did a whole heap of nasty ahead of their case which is the key differentiation point between then and Apple's actions now.
