The Raspberry Pi-based devices fail to pass the Google certifications tests due to low GPU performance. Thus, there is no possibility to include proprietary Google applications (Playstore, YouTube, Calendar, Maps, etc.) into emteria.OS.
But there are perfect alternatives to most applications and features GMS provides.
Instead of using Google Playstore, we recommend using F-Droid:
F-Droid is an open-source app store for free Android applications where you have access to over 1200 ready to use applications. The main repository, hosted by the project, contains only free and open source apps. Your own private repository can easily be integrated into F-Droid and provide app updates to your devices in the field.
For more information, read the introduction to F-Droid.
Instead of using Firebase Cloud Messaging (FCM), we recommend using UnifiedPush:
UnifiedPush is a decentralized, open-source push notification protocol. It can be self-host and used cross platform.
For more information, go the UnifiedPush