I have an old ThinkPad 11e running Debian that I have repurposed into a home server. It’s only supposed to run TVheadend. I don’t need any other services for now, but later on i might add a few using docker.
Is it enough to set multiuser.target as default to disable gui and keep the system always on?
How can I disable all unnecessary services and minimize power usage?
That’s typically a feature for servers or business desktops. Maybe your laptop has it, just look into the BIOS.
As I wrote in my other comment: try to be realistic about your needs. Chances are, pressing the power button every few months (if at all) is perfectly fine for your use case (and most others here).