Enable In-App Purchases
To try to enable IAP I added the NanoDroid repo mentioned here: https://github.com/microg/android_packages_apps_GmsCore/issues/309#issuecomment-446926321 But the FakeStore and NanoDroid Patched Play Store's signatures don't match so I couldn't just upgrade. An easy solution to give users the option to enable IAP would be to repackage FakeStore app with a signature that matches the microg signature and likewise the NanoDroid Patched Play Store found on their repo: http://www.nanolx.org/fdroid/repo/
This way any CalyxOS user could either keep FakeStore or they could enable IAP by adding the NanoDroid repo and upgrading FakeStore.