Alternatives:

• Fastmail instead of Gmail
• INWX (and own a domain) instead of substack.com
• Mastodon and a bit of Bluesky instead of Twitter
• Nextcloud instead of Google Drive
• Collabora instead of Google Docs
• Immich instead of Google Photos (with Google Takeout https://takeout.google.com/settings/takeout/custom/photos). Ente seems also a good alternative.
• Nextcloud Deck and Nextcloud Collectives instead of Notion.
• Forgejo (or Codeberg as german forgejo isntance)
• Web search: not so much great alternatives. Kagi (but US-based), DuckDuckGo, Ecosia, Qwant
• Firefox instead of Chrome. Hope for Servo or Ladybird.
• Qobuz instead of Spotify. Also an owned Jellyfin streaming server.
• Nextcloud Polls instead of Google Forms