What's wrong with encrypting your passcodes, seeds, etc. in your will?
Or actually if you want to ensure that you can release this, just create a time-based message to which you have to refresh every [duration]. If you're dead, it's sent!
What you describe is essentially a dead man's switch. There are several online sites, I use at least one, in addition to Google's Inactive Account Manager = euphemism for a dead man's switch that waits at least 3 months of inactivity.
It's as simple as a "Send Later" .. which even Gmail has now. Just make sure your message is encrypted, and teach your beneficiary how to decrypt it. Or if you need to make it simple, a pointer to a second factor or object you know only they have, like the password to your encrypted USB device stored somewhere she knows. You'll have to update this often, depending on your circumstance.
Some people just do plain paper wallets or seed phrases as cold storage and that also works.