To say the Fenix 7 tracks tennis was pretty low effort from Garmin : r/ Garmin
F3b Sports+ | Garmin Connect IQ
Garmin Brunei - Track your moderate and vigorous activity minutes, and see when during the day you earned them and during what activity. You can even add them as a data field
I have a dream ! Tennis as an activity - Garmin Connect Web - Mobile Apps & Web - Garmin Forums
TRACK ANY SPORT With Your Garmin Forerunner 245 | How to Create Custom Activities - YouTube