Miniflux
I had used multiple Atom/Feed Readers in the past, including command-line based Newsbeuter (and Newsboat), Elfeed as part of Emacs and Reeder on Mac OS. But, my main problem was that none of them support syncing to my Android phone. There is also no integration with Instapaper.
I discovered Miniflux on the Awesome Self-Hosted page. It is a minimal feed reader web application. After some reading, I found out that it is a Golang rewrite of Miniflux v1, that was in PHP. I have a sweet spot for Golang software. The software ships as a statically linked binary that is easy to install on the server. The developers of Miniflux provide a hosted service for just 15$/year with a 15-day trial.
I decided to give it a go and signed-up on the hosted service for a trial. My first impression of Miniflux is how fast it is. The Miniflux web interface is intentionally minimal, and the webpages are rendered directly on the server-side. The web interface is a Progressive Web Application. Miniflux has built-in integration with popular services like Pocket, Instapaper, and Wallabag.
Once I was convinced, I decided to install it on the server. Miniflux intentionally only supports the PostgreSQL database. The database is easy to install using the package manager on Debian. The setup instructions on the website are easy to follow to set up the database and create the admin user. The admin user can then add more users from the web interface directly. For private use and additional security, you can setup Cloudflare Access in front of Miniflux for authentication.