iOS 15
Route and automatically answer calls on iPod touch
You can automatically direct the audio of FaceTime calls to the iPod touch speaker, a Bluetooth headset, or your hearing devices. iPod touch can also automatically answer calls after a specific duration.
Go to Settings
> Accessibility > Touch > Call Audio Routing, then choose an audio destination.Tap Auto-Answer Calls, turn on Auto-Answer Calls, then set the duration of time before the call is answered by tapping
or 
.
During a call, you can switch the audio routing from your hearing aid to the iPod touch speaker by removing the hearing aid from your ear.