I carry my license, credit card, medical insurance card and some cash in a small zip-lock bag.
It goes in my jersey pocket on road rides and shorts pocket on MTB rides.
I carry them on my body in case I am separated from my bike.
The cash is to buy food and drink, in case I didn't bring enough, or want a treat.
Most of my helmets have a sticker inside with contact information.
I also carry my cell phone for emergencies and because it's my camera.
I'm cautious about tracking apps because they could run down the phone battery.
I should find a good APP.
I ride with a heart rate monitor for medical reasons. I can ride further and longer if pay attention to my heart rate.
When I ride from the bay over the hills to the coast I'm on the smallest, most remote, backroads and there are large areas without cell coverage.
Most of these rides I am solo.
I have a Garmin InReach satellite communicator I use for motorcycle adventures.
It allows you to send and receive text messages at anyplace on the planet.
The text messages include your location.
I'll carry the InReach on solo coastal rides.
Only carry what you think you can use to keep yourself alive to ride another day.