That's a nice self contained application. A fun project with a dark twist! Can I pre-order my nanochip?
As you say, there are a few programs and online services that can do similar things but they can be expensive. And you have to trust them.
Since each person's situation is different I imagine some flexibility in the unlock logic would be useful. For example, options for needing a solicitor or 2-of-n family members to hit a "he's kicked the bucket" button in their app, or send a "he's popped his clogs" email.
I had a similar idea to this using a blockchain-based private storage protocol I built called Bubble. Bubble Protocol is a general purpose private data layer for decentralised applications, like a Web3 dropbox with smart access controls. It holds data in off-chain private 'bubbles' and holds the access control logic separately on-chain in a smart contract. One smart contract per bubble. A bubble's smart contract can be custom designed for the specific application and describes the life cycle of the data in the bubble, including who can access what files, when and under what conditions.
In the case of a posthumous automation app, the smart contract would contain the unlock logic and would be kicked by the app. An off-chain bubble storage service (could be your own server or a cloud service) would store your encrypted bubble. Once unlocked, your family and friends can access and decrypt their area of the bubble.
Cheers
