As others have said, debian is very minimal, so If you would prefer to setup and configure the whole system yourself, debian is a good choice.
Personally, I prefer fedora server. It comes with more things configured out of the box (zram and sysctl configs for example) as well as better security defaults (selinux included with proper policies) and first class support for container infrastructure. Ultimately you could achieve a similar end result with debian, but for my homeservers I prefer to let the fedora team handle most of the system configuration for me.
I don’t have a specific answer, but you could also look for tools that schedule reboots. If I remember correctly, a fresh boot has the same effects as lockdown mode. Fingerprint is not accepted, and the device contents remain encrypted until you unlock the first time.