apps.microsoft[.]com/store/detail/wsa-sideloader-apk-installer/9NMFSJB25QJR?hl=en-us&gl=us&cid=ghreadme&rtc=1
Microsoft's been continuing its work on Win11's optional Subsystem for Android, e.g., it's easier to install & they've been updating the version of Android it uses, but since it's not officially backed by Google, you're still limited to a selection of apps from the Amazon App Store. WSA Sideloader makes it easier to *try* and get around that limited selection -- I emphasize Try, because many apps in the Google Play Store rely on additional services only provided by Google, and those apps can't work in WSA because those services are missing. [There are ways to get around that and get those services working with WSA, but those methods are involved enough that you're probably better off to just use something like BlueStacks (bluestacks[.]com) if you really want or need an incompatible app or game.]
The biggest hassle side loading Android apps, whether the device is a Kindle, cell phone, or your PC / laptop, is that you need the setup or installer file, which is referred to as an APK, e.g., SomeGame.apk. Google won't let you just download them. There are sites offering APKs that you can find with a quick Google search, but you have to be willing to accept the risk -- even the official Play Store isn't 100% safe [security folks are always finding malware in the store's hosted apps], and you have little to no assurance that any APKs you download haven't been tampered with. What I generally do is use an APK extractor on one of our devices that's been installed from the Play Store -- you install the app / game you want, then run the extractor app, which will save the APK so you can transfer it to another device, like your PC.
WSA Sideloader is also available on GitHub, & by using the WinGet app, but the developer recommends you use the version in Wndows Store.