this comparison looks good, but it claims that there is no opt-out for microG in /e/OS. yet, in the app settings i can simply disable microG completely. is that not sufficient for opt-out?
Perhaps there are some settings that still rely on Google that can’t be disabled, such as push notifications. Most if not all apps from the Google Play store will use their framework to send push notifications to your device. If you get notifications on messaging apps with microG disabled, this could be an indication that your device is still using Google services under the hood