That's one possibility, yes. My gut feeling goes like this:

If you've been training without for as long as you can remenber and having or not having such a device has zero effect, you're the adult in the room and this is not about you.

There's allways the guy who liked the colour. That's not about him either.

If you bought one to help you keep going, I'm afraid it will help you as long it is a novelty, data is a novelty, your "network" is a novelty... Past that and the efect will vanish like hot water cooling. A trick that might help is to get someone you care about to share your progresses and achievements (the data) like a nice training partner or a family member, or someone with the same desiese as you if that's the unfortunate case.

If you're really excited about your workouts and bought one to help you even more, I'm afraid you'll realize the novelty efect will wain down as you get to know your mesurements by heart as well or predict them sometimes more acurately than the device. The exceptions are professionals - those don't count here.

If your trainer made you buy one but he's not looking at the weights yout lift or counting the reps and couldn't care less about the records, but he's counting very closely and keeping track of how much time you're spending in that particular hart rate zone or other seemingly weird mesurements, you're golden. Don't (or do, rather, in the positive way) question the need for such a thing, never leave that guy (or girl), never miss a session.

There’s a few on F-Droid.

Let's just help this guy.

Here's one I trust: FitNotes

Like @[email protected] said, there are several.