I have a Garmin Forerunner 55. It was the cheapest Garmin available at the time of purchase and is basically a fitness tracker. It replaced my ancient Polar which used a strap sensor to measure heart rate. When the Polar died I was looking around for something that would measure my pulse without too much hassle and settled on the Garmin. I like it. If you're concerned about privacy, the watch won't upload any data unless you sync to their phone app which it does via bluetooth and the app uploads to Garmin's website. It's reasonably accurate on pulse and distance traveled(running, biking, walking). It keeps track of your resting heart rate and computes a seven day average as well as keeping track of your sleep time(total, rem and deep). However, to get the most out of the watch you really need to install the Garmin app on your phone and periodically sync the watch with it. That necessitates creating an account with Garmin but gives you access to their website where your fitness database is much more extensive with all kinds of graphs and data. This, of course, does raise privacy concerns, but in my case I feel the tradeoff is worth it.
The watch connects to a PC via usb and data can be downloaded off the watch. I used an opensource application, ZombieTracker, which can read some of the most relevant data off the watch(times, distance, heart rate, course maps) and keep track of it all in its locally stored database. It's a decent alternative for those with privacy concerns:
https://linuxiac.com/ztgps-linux-fitness-tracker/
