I am using a Garmin watch when I need TTP. The companion app can be run in a separate profile (or even an old phone, or chromebook, or maybe Android Studio with bluetooth). I'm not sure how often the watch needs to sync to keep TTP working. I'm hoping that Garmin is a smaller fish in the data-broker economy (than Goog/Appl/Samsung).
I'm not logging any activities, though I haven't read any analyses of whether Garmin is secretly logging GPS, then uploading that when it syncs.
Great! I'll look at my Wards and see if there are markings on the top of the needle bar.