Over-the-ear hearing amplifier that fits narrow ear canal

My dad visited a hearing specialist who basically told him he was out of luck because even she had trouble getting hearing aids into his ear. Whatever we’ve tried he has rejected. However, he can fit Apple Airpods into his ears. He would prefer some sort of headphones.
I can’t seem to find any simple solutions that would fit like Airpods or headphones. It is frustrating that something like this doesn’t seem to exist, because it should be so easy. Why do headphone hearing amplifiers have to have a separate mic and cables and a box you have to stick in your pocket? My bluetooth noise-cancelling headphones have a mic input right on the headphones. Why can’t they just program them to amplify external noises instead of cancelling them?
Am I missing something? Does anyone have any recommendations for hearing amplifiers that would fit more like Airpods or headphones?

You can try Jacoti ListenApp for free. It is available for iPhones, but not Android. It will give you an idea of the advantages / disadvantages of headphones. I used it for a bit with a Shure MV88 mike attached to the phone. The audio quality was excellent.

I eventually got Costco KS-10 hearing aids. I had a rough start, but after about 3 months of use, I would not do without them. The phone, and headphones, were a bit cumbersome to deal with. Also constantly explaining why I was wearing headphones in the middle of a conversation.

Bose hearphones are great.