Hi Chris Canaday
welcome to the Apple (user-to-user) Community!
Re: "AirPods Pro used as hearing aids. My issue is that when I'm not speaking, they seem to go into some sort of sleep mode, like they turn off to external inputs." ....
... "When they are in external input mode, the settings automatically enter transparency mode, which makes sense. Is this how they are supposed to work?"
Thank you for the clear description of your issue, and your question.
Am no expert in this area, yet your question certainly deserves some response.
Those, like yourself, who actually require hearing-assistance can often contribute most to improvements, either in how-to-use, or through feedback to Apple.
I expect you already have the latest AirPods Pro 2 firmware update, 7B21
Else: please see: About firmware updates for AirPods - Apple Support
Wondering if you have looked through all the controls that are available:
Eg: Apple support's online article: Use the Hearing Aid feature on your AirPods Pro 2 - Apple Support
says:
"Adjust amplification level, balance, and more in AirPods Pro settings
You can adjust settings like amplification level (how much your AirPods amplify the sound around you), left-right balance, tone, and Conversation Boost on iPhone, iPad or Mac (requires macOS Sequoia 15.1 or later). For quick access to settings, you can use Control Center to adjust settings."
Hearing Aid Feature : Instructions for Use (IFU) https://regulatoryinfo.apple.com/ifu/haf
Eg: Page 7 :says:
"Using the Noise Control Modes with the Hearing Aid Feature
In order to make the Hearing Aid Feature active, the Hearing Aid Feature must firstbe enabled
Afterwards, the Hearing Aid Feature is only active when the Noise Control Mode has been set to ‘Transparency’ mode - When the Noise Control mode is set to ‘Off’, ‘Adaptive’ or ‘Noise Cancellation’, the Hearing Aid Feature can remain enabled but will not be active. While in‘ Adaptive’ and ‘Noise Cancellation’, users will be able to use these modes as expected without HAF active."
___________________
If nothing above helps, there is a web-form online for feedback to Apple: Feedback - AirPods - Apple
They will likely not reply, yet your feedback will reach those working behind-the-scenes who can make changes, if others are experiencing a similar issue.
For more immediate support: You may want to contact Apple's Accessibility Support Team:
See: How to contact Apple for accessibility support - Apple Support
or
Apple's Accessibility Support Website (NB: You can "Get Support" from the link at the bottom of their website:)
Accessibility Support - Official Apple Support
or
AirPods Support Website: Find all the topics, resources, and contact options you need for your AirPods...
AirPods Support - Official Apple Support
All the best :-)