Debian Installer is a complicated tool. I am trying to figure out where to start. Well, some starting pages:
- DebianInstaller: starting page for many things debian installer
- Debian-Installer: Building the installer yourself
- DebianInstaller Preseed: various ways to get preseed files to the debian installer
- Debian Testing Install
- Netboot: the daily release version
- Debian Installer Internals: read to understand what happens during the installation process
- Netbooting and Firmware: not absolutely required as there is a non-free cdimage debian repository from which boot .iso files can be obtained with non-free firmware.
To troubleshoot some recent Buster installation problems, I know now to use DEBCONF_DEBUG=5 in my boot files.
Debian Git Server, which includes debian installer packages.