Foundation passport is FOSS offline signer.
I use a RoninDojo Tanto as full node hardware/software. Incredible stack.
I prefer a full node that is just a node, not anything else.
You can DIY it on a single purpose computer or buy a very similar build from the node legend
nostr:npub1txwy7guqkrq6ngvtwft7zp70nekcknudagrvrryy2wxnz8ljk2xqz0yt4x