All good suggestions, but mine is: Start with something redundant.
Do you use Google Drive? Set up Nextcloud and use both for a while.
Also, decide on user management first. It’s way better to have a central system for managing passwords/etc. Personally I use an Active Directory based off Samba4: https://github.com/Fmstrat/samba-domain because it’s got LDAP and expandable with Keycloak to OAuth and OIDC. This may sound overwhelming, but once you learn what they are, its fairly straight forward.
Go on a vacation with a dumb phone. Make sure there are tons of active activities to wear you out. Bring a friend if possible who will do the same.
Before you leave, set up some form of blocker/parental controls and have someone you trust set the passwords.