Lost iPhone what to do

I left my iPhone in an Uber. There is a low probability, but still a probability that I will get it back.

Meanwhile, out of necessity I bought a cheap minimal phone and had my phone number reassigned to it.

What is the status of my iPhone? I doubt the battery has died. It still shows as a device that I am logged into with my Apple ID. I have not initiated any "erase," action, nor have I removed it from my devices.

As I scan the apple site collecting possible actions, I sense there is no way back from those actions.

However, I did see a "report it Lost" function that seemed harmless enough. When I say harmless, I mean Im trying to not to paint myself in a corner if the Uber driver turns out to be a good natured sort and I actually get it back.

I hope to know that answer in a couple of hours. Meanwhile I do feel exposed. So, is it "report lost" or some other approach? Thanks in advance for anyone compelled to assist. Greatly appreciated.