Earlier quoted context omitted.
For Google docs I switched to using a Synology server. Very nearly as good (better, in some ways) and I don’t have to worry about what Google is up to. The up-front cost and setup time is a stiff investment, but I’m much easier in mind now. The other side of the coin is my wife’s gmail, which is going to be deleted come May. So... we gotta figure that out.
What sort of collaborative editing does Synology allow? Is there a Nextcloud / Owncloud alternative to Docs / Sheets for collaborative editing?
Yes, NextCloud and Owncloud both integrate with OnlyOffice Community Edition[0][1] which supports collaborative editing of text documents, spreadsheets, and presentations.