Here is a summary of my personal most important hardening tips concerning the SSH-Server. I want to share the steps with you, and also take them as a reminder for me ;).
I want
Requirements
* Raspberry Pi (Model doesn't matter)
* SDCard running Raspberry Pi OS (formerly known as Raspbian)
* Basic OS Setup already set (e.g. Wifi/LAN, SSH)
* optional: Set up Dynamic DNS
What I want