My personal checklist and research to de-google my stuff.
Updated: Jan 19, 2020.
Main things that were keeping me on the stock Google Pixel 3 Android OS:
I set up a personal Nextcloud server that runs on my old desktop PC at home. Nextcloud provides sync for your contacts, calendars, and files and gives the most bang for your buck in taking back some privacy from Google.
I downloaded all my Google data with Takeout and imported it into Nextcloud. New camera pictures are automatically backed up to my Nextcloud instance.
My @kirsle.net domain used to be hosted on Gmail, and self-hosting e-mail is a lot of work, so I rent email hosting with a third-party (Rackspace) that has no incentive to read my emails. My old @gmail.com account is just an e-mail inbox and can be added to any standard email app.
DuckDuckGo replaces Google Search. It generally works well enough, but if I don't find good results I append "!g" to my search and it takes me to Google, but still most of my searches do not go to Google.
YouTube Vanced is an alternative YouTube app for Android and can work on a de-googled phone. It's blocks ads and can play videos in the background and seems to support signing in with a Google account via microG.
On mobile Linux, YouTube.com works okay in Firefox on Pinephone but videos in general aren't hardware-optimized yet.
Google's web services are easy enough to replace, but I also have several Chromecast dongles and a Google WiFi mesh router that I wanted to keep working.
There aren't any good (free, private) alternatives to the Chromecast that don't just replace Google with a different corporation that collects your data. A raspberry pi or old-fashioned "TV PC" is a step backward in usability.
My current main phone was a Google Pixel 3 running the stock Android OS complete with Play Services and Chromecast-able apps like Netflix and Hulu. But I decided I could at least sign out of Google on this phone so whatever data they collect shouldn't be associated to a user account. This meant I couldn't use apps like YouTube or Gmail (which need you to sign in, and signing in logs your Android device as a whole in) but instead my Nextcloud instance provided Contacts & Calendars and I used alternative apps from F-Droid. For Gmail I installed a standard e-mail client app.
Currently, my Pixel 3 is running a de-googled Android ROM (GrapheneOS) which is privacy-focused and has no Google apps or services installed. It can't Chromecast, and many Play Store apps don't function, but some of them do work well enough: Slack, Discord, Kik, Venmo, DoorDash and Zoom; just without push notifications in many cases.
I also had a dusty old Pixel 1 lying around that I had initially tested de-googled Android on. I reinstalled the stock Google Android OS and this phone is my "Chromecast controller" -- WiFi only, mostly stays at home, and runs the few apps that require Google services.
The need for a Google device to control my Chromecasts isn't going away soon, but I may be able to replace the de-googled Android with a Linux phone soon. I have the Pinephone and the software is getting good and it works with T-Mobile reasonably well.
See Self Hosting for my experiments running LineageOS without Google Services and the options for self-hosting crucial web services.
Without Google Play Services some apps won't function correctly. I need to make sure the apps that are important to me work or have workable solutions.
See also: my App Compatibility Table