Also late to this discussion…
I first thought of and executed a plan in 2017 when North Korea fired two missiles over Japan, one in August and one in September, and I had to go for meetings in Tokyo and Kobe that October.
I decided for the system not to be overly complicated and created an encrypted thumb drive which contained instructions in plain text and RTFD’s on how to access my 1Password, bank details, etc and step-by-step instructions on how to deal with life insurance, stock options, broker, crypto wallets etc. (I call this my “Red Book”.)
I thought my family would not be interested in 99% of the data I have stored, except for my “archived correspondences” which contains digitised letters, emails, forms etc going back to the 1990’s. In setting up DT3 I made sure that this was “Indexed”, and hence access would be simple regardless whether DT3 is used. In any case, my thumb drive contains instructions on where the folder is and how to access it.
Before I left I told my wife where the thumb drive was hidden in my study, gave instructions, and put the password to access it in her 1Password database.
So now I remind myself to update the thumb drive once in a while, since a system is already in place. Soon I will give my daughters similar instructions on how to access “the Red Book”.