It means that if I died they will be in an ocean of trouble if I did not take steps to facilitate the transition.
The first part is to have a paper backup of everything important, and keep it up to date.
The second, requested by my wife, is a tutorial on how to de-automate the house and what things they should worry most about (moving the self-hosted Bitwarden and making sure domains and email are paid for).
This preparation doe not bother me at all on the emotional level but rather on the documentation one...
GitHub or something as a poor mans might work for some time.
Archive sites could be around.
Or start a religion.
There are however legal rules against trusts in many jurisdictions: https://centaur.reading.ac.uk/100782/1/Article%20-%20The%20r...
So your best bet is to establish a community of people interested in preserving your website, or websites in general, and have them run a long term nonprofit for that purpose.