What about creating the bonds via account creation.
So for example 'bond-000000' would be the first minted bond... then 'bond-000001' the second etcetera.
Not sure if it is the best approach but it would offer a lot more functionality than a Layer one (or Layer 2) NFT.
The account isnt tradeable. The idea of the NFT (bond) is to provide liquidity if the person who lock up for a year wants to sell it into the market.
Maybe an account could be made tradeable via the account recovery function.