CalyxOS comes with two open source app stores F-Droid and the Aurora Store. F-Droid is an open source app store that will work on any version of android and comes preinstalled on CalyxOS. All apps in it are free and open source and will work with or without microG. Aurora Store is an open source mirror of the Google Play Store that allows you to anonymously install apps from the Play Store. Many of these apps will work as normal. Apps that require Google Play Services will require microG. microG is an open source Google Play Services alternative that anonymously substitutes the functionality of Google Play Services allowing many, but not all, apps that rely on Play Services to work. Be sure to check app compatibility with Plexus a free and open source tool to track app compatibility on deGoogled Android phones.  If you have questions about  compatibility or alternatives to your favorite apps email us at support@privacypractical.com