Family tech support:
* old laptop decrappified and updated. Four versions of macOS out of date, which is odd as is was set to do automatic updates. I have not taken it apart to work out why the trackpad doesn't work, and thank goodness for keyboard navigation while I got the external mouse working.
* new laptop set up, and migration complete.
* phone updated.
* tablet needs replacing.
That should tide them over for a few months.
@neil IME, touch pad issues on Mac laptops are often battery swelling issues. Any chance you checked to see how the battery was doing and if the case felt a bit pressurized, or didn’t quite sit flat on a table?