Using AirPods Ultra 2 as hearing aids without iPhone

Using AirPod ultra 2 as hearing aid: Will they still work as hearing aid if I leave my iPhone at home? I need the iPhone to set them up. Can I then use them as hearing aids while out on a bike ride without my iPhone?

I need hearing aids. I have expensive ones, but I'd prefer to use the iPods as hearing aids. I want to leave my phone at home, and continue to wear the iPods while I'm out & about. I do not have a watch. Can I use them as hearing aids as is? I know I won't be able to adjust them without a phone or watch.

[Re-Titled by Moderator]