Yes, this has been known for many years.

Most rental car companies don't bother setting up fleet services for their connected vehicle services. They require infrastructure that car rental companies don't seem to consider important.

I've used this mostly to remote start my rental car in cold climates. I delete my account after my rental is done, though I've learned recently that some providers, like Hyundai, make this SURPRISINGLY difficult.

The only exceptions I've seen to this are FordPass with Avis (this was locked down a few years ago) and Tesla with Hertz (before they unloaded them all).