Simplify multiple fresh installs onto different hardware

I've read through this: https://unix.stackexchange.com/questions/707610 but most of the discussion is over my head. My computer usage has greatly declined since retiring 10 years ago, and I haven't kept up. I'm primarily a command line user, since the mid 80's. I'm looking to greatly simplify my process for putting fresh single-user installs onto new hard drives in my various computers (all amd64 desktops/laptops, different videos cards etc), plus hopefully producing a custom live-dvd. Old hard drives will get archived. Some machines are not networked in anyway. All the hardware is old, e.g. 10-yrs. Last time I went through this was maybe 5 years ago. First phase is the fundamental installation to create a bootable machine, Debian 11.7 with XFCE, with machine specific customizations such as partitioning, and generic customizations such as including/excluding various packages. Second phase is a bunch of customizations, such as non-graphical login, sudoers list, fstab, gpg, additional package installs using apt, software config files, etc. In the past I've kept a written log of these details on the first install, then tried to manually follow the log for subsequent installs. Is there a simple auto-log feature or some such, especially the second phase? something more encompassing than bash-history? Or a way to to create a system-diff between end-of-phase-one and the end-of-phase-two, then apply that diff on subsequent machines?