Beyond the IoT Core version, perhaps it has to do with an exclusivity deal with Microsoft and Qualcomm since the Raspberry Pi runs an Arm-based processor.
This isn't explicitly a new article, it was published in 2021, but since there's no explicit date on when that deal will or has, or if it'll expire, perhaps we should now start seeing the fruits of that deal expiring.
An excerpt from the article:
"Last week, we reported that MediaTek is planning to build a chipset for Windows on ARM. As it turns out, the Windows on ARM chipset space could be even hotter than that, because there's a reason that we've only seen Qualcomm SoCs in ARM PCs so far. Qualcomm actually has an exclusivity deal with Microsoft for Windows on ARM, and speaking with people familiar with it, we've learned that the deal is set to expire soon.
