Seamless interaction between phone and Windows is their mobile strategy. Windows 10 already did a lot in this direction, with the ability to link a phone, or to cast the phone screen onto a dedicated window. Allowing apps to run in Windows is a logical next step.
The other part of their mobile strategy are tablets or tablet-substitutes. Basically their whole Surface lineup, which Windows 11 aims to improve.
Except for one small detail, they appear not to support the latest Surface Go 2 tablet! According to the PC Health Check tool, my maxed out Microsoft Surface Go 2 that I bought new a few months ago (with 8GB RAM, 64-bit Intel core m3 processor) is NOT supported to upgrade to Windows 11. Wow. Their system requirements tool also doesn't say why my tablet doesn't meet the requirements, just that it doesn't.
I believe Apple is working on getting iOS apps working in future versions of Mac OS. Microsoft being able to run Android apps in Windows is probably in part a response to that.
You can already install iOS apps in the current version of macOS, but only on Apple Silicon machines and app developers can decide whether their apps show up on the Mac App Store.
Interesting, why would they do that? I mean it's nice ;) but, is this the new MS mobile strategy? Android?