TLDR; I want to fully be self custody and at the same time contribute to layer 2 of BTC. If you have a link on helping me achieve this with my own hardware please respond.
I would start with this:
Get a Raspberry Pi and set up Raspibolt or Raspiblitz.
and I would add a hardware wallet on top of this, but since you have a strong opinion like
Fuck Ledger, I want to rely on my own hardware... My own hardware I built with my own hands.
I will recommend either a/another computer (or USB stick with a Linux) that you would leave forever offline and use as cold storage, either a
SeedSigner-like device.