This is from 2023, but this might still be a good read on how to get to a very low watt idle build, there’s a few more post on other older builds on that blog as well: https://mattgadient.com/7-watts-idle-on-intel-12th-13th-gen-the-foundation-for-building-a-low-power-server-nas/

The Linux Foundation has a mentorship programme which is really great, might be worth a look, although I am not sure how easy it is to get accepted: https://docs.linuxfoundation.org/lfx/mentorship/mentees

The energy prices in Sweden were also mostly negative yesterday, and today as well. Although probably not quite as much as in Finland.

Use Clevis either with TPM or Tang (remote server) https://github.com/latchset/clevis