I do sometimes. I own an HRM, but I don’t remember to wear it about 50% of the time.
Garmin Edge 700, just because I like fancy tech toys, and someone at work told me to get it. So after a year of hearing how great it was, I finally splurged. I love using it for GPS too sometimes, and I took it on a vacation to use in a rental car. When I ride, I usually leave the display set to the following 8 fields: speed, cadence, HRM, average speed, time of day, ride time, ride distance, and one other less memorable field.
I’ve never used a training computer. I do have a trainer, but I don’t use it often. I used to hook the bike to it in the winter with the plan to use it, but never actually rode. Waste of time for me, and just made bicycling outdoors less accessible during the winter months. Now I just have more cold-weather clothing, so I will probably ride more in the winter this year.
I only use the CGM for ‘now’, not for training purposes. My sugar during rides doesn’t fluctuate enough to do any calculations with. I also don’t ride for more than an hour at a time most rides. Really most rides are the 26 minutes in to work once a week or so. I have the Medtronic Realtime system for CGM with a Paradigm 522.