@johan_bavaud Wow. Congratulations on the execution of this.
Have been toying with this idea back in 2005 (reason I registered the main 'memente' domains in that year) in the Netherlands but found a lot of resistance with the legal side of it. Notaries really had no clue about the digital aspects. Recently posted about this as the "under the bus scenario" amongst solopreneurs over at Indie Hackers, https://www.indiehackers.com/post/under-the-bus-do-you-have-a-worst-case-scenario-plan-bcc11cf8e5.
You seem to tackle the hurdles very well: legally valid, confidential and secure.
What I would love to see is an open source element that other services can easily prepare for this scenario.
Have added you to the list (don't judge me please, it's really a list) over at https://memente.com... the Swiss element has a lot of potential to pull it global.
One more thing ref another comment on blockchain: there is actually a lot to say for that. But it would require tokenization and the commitment of the legal parties involved. We're not there yet but that seems like a logical future.
Not planning to do anything in this area myself anymore and happy to share the ideas I had for this. Please get in touch.