My smartphone *is* my bike computer and emergency call center. A cheap $10.00 handlebar mount securely mounts my Motorola Moto z3 phone. All sound levels are turned off. If a call come in, I won't know about it or be bothered by emails, etc.
I use the Wahoo Fitness app to read off of the Wahoo HR chest monitor. Syncs with Strava.
I also wear 24/7 a Fitbit Charge 4, which gives another viewpoint on the ride, but more importantly, monitors caloric intake and sleep studies. This, too, syncs with the phone, so that at the end of the ride I have all the data online by the time I open my browser.
No GPS issues on the country roads I ride.
My rides are short, and will continue to be until I can build up my stamina and leg strength to where it was before the accident. Even then, I don't have the time to ride for hours--too much to do.
Everyone has their own notion of what is important: safety, security, monitoring. This works for me. Better than using an expensive bike computer that still requires cell phone connectivity at some point, and if like me, you never want to be out on the road without the means to call for help---or get a quick phone pic of a driver being an ass.