I don't get what you are saying here re no sovereignty with no (custom) hardware.

Grab the Bitcoin white paper and an airgapped PC with a fresh Debian install.

Implement the algorithm(s) in the white paper to generate yourself a private key and then a wallet address from that.

Send bitcoin to that wallet. Write down the private key and wallet address, store it somewhere safe, bury it in the garden, whatever.

No special hardware is required for any of this...

Or am I missing something?