Thanks @kugiigi and @arubislander , caveat noted. As an update for anyone trying to do similar it seems GPS is not working with the App in Focal (so my search for a Focal-based app to record GPS (.gpx) track continues.

(See also my other post on "Libertine fails to install a package because of permissions related to the creation of a directory /run/gpsd. How do you fix permission errors related to gpsd?" - https://forums.ubports.com/topic/9175/libertine-app-install-run-and-remove)

Here is what happens with Activity Tracker (a Xenial based app running in Focal):
• map show API Key Required
• clicking on saved activity shows spinning wheel
• importing .gpx file shows correctly but clicking on saved activity shows spinning wheel
• Recording activities (screen on or off, app on top or background) shows no data for speed and altitude also distance 0.
• Map shows whatever you set it to (starts at Trafalgar Sq in London.
• Time advances but seems to stop advancing when screen is off (locked).
• Ditto for “i” Track Info when looking at gpx track– spinning wheel. After stopping record:

cd ~/.local/share/activitytracker.cwayne18/ phablet@ubuntu-phablet:~/.local/share/activitytracker.cwayne18$ ls -la total 40 drwxrwxr-x 2 phablet phablet 4096 Jul 27 19:31 . drwx------ 37 phablet phablet 4096 Jul 27 17:50 .. -rw-rw-r-- 1 phablet phablet 341 Jul 27 19:10 1690499407.gpx -rw-rw-r-- 1 phablet phablet 341 Jul 27 19:31 1690500673.gpx -rw-r--r-- 1 phablet phablet 16384 Jul 27 19:31 activities.db -rw-rw-r-- 1 phablet phablet 8 Jul 27 17:50 .dbfixed -rw-rw-r-- 1 phablet phablet 8 Jul 27 17:50 .dbfixed2

1690499407.gpx

<?xml version="1.0" encoding="UTF-8"?> <gpx xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.topografix.com/GPX/1/0" xsi:schemaLocation="http://www.topografix.com/GPX/1/0 http://www.topografix.com/GPX/1/0/gpx.xsd" version="1.0" creator="gpx.py -- https://github.com/tkrajina/gpxpy"> <trk> <trkseg></trkseg></trk></gpx> 1690499407.gpx (END)