We care about this porblem and are actively working on it, like the OP we also settled on shamirs secret sharing with a time lock mechanism.

However, there is still the issue of the service provider going offline or out of business which we don't have a solution for yet.

We have started with a good password manager and will be adding digital inheritance/social recovery soon! [0]

Take a look, thoughts and feedback welcome.

[0]: https://saveoursecrets.com

services going offline is a big concern for me! that's why my solution is offline first, I like the idea of the encrypted backup living in my friend's email inbox and working entirely without internet. a true hard copy.

for the time lock mechanism, how do you go about it? I'm interested in exploring using drand time lock, but that also relies on the service continuing to run (which is admittedly very likely) https://github.com/drand/tlock