Thank you kindly for supplying us with your added info.
Re: iPhone 14, iOS 26.3.1
Your iPhone's hearing software is quite capable of controlling Mfi compatible hearing-aids.
An iOS update is available for the iPhone if you want to check in Settings > General > Software updates.
(Reminder: It is always wise to back-up iPhone first if you choose to update.)
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Re: "my Audicus Omni2 hearing aids are not on the list of Apples Mfi compatible hearing aids".
OK. Thankyou for checking. That means, apart from using Bluetooth, the iPhone's inbuilt hearing software may not be of help in controlling the hearing-aids, so the "Hearing Remote" app is likely your only means of control.
I looked at the manual for the Audicus Omni2 hearing aids online.
https://www.manualslhttps://www.audicus.com/support-center/
I notice it said the app is compatible with Android phones. (Nothing about iPhones). Seems the app may not be fully capable of controlling your hearing-aids while connected to an iPhone.
Page 18 said: Note: this app may not be compatible with all smartphones The free Hearing Remote app can be downloaded from the App Store (iOS) or Play Store (Android). Find links at audicus.com/app
Requirements for the Hearing Remote app: Android version 10.2+ version 6.0+
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Re: "While sitting watching TV, Voice Control tried to call random people no less than 12 times in an hour".
The Manual's "Technical information":
Eg: says:
"However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:
Reorient or relocate the receiving antenna.
●
Increase the separation between the equipment and receiver.
●
Connect the device into an outlet on a circuit different from that to which the receiver is connected.
Consult the dealer or an experienced radio/TV technician for help.
Radio information of your wireless hearing aid:
Antenna type" Resonant loop antenna
Operation frequency: 2.4 – 2.48 GHz
Radiated Power: <2.5mW
Bluetooth: 4.2 Dual-Mode"
Am no expert in this area ... Sorry to say there may not be much that Apple users can help you with here. Your hearing-aid specialist, or hearing-aid supplier or manufacturer, may have advice or tips.
Re: "Siri was constantly talking in my hearing aids while at lunch with someone at random times, as if I had asked it to look up something".
Depending on your iPhone settings, simply turning an iPhone face down may help ensure Siri isn't mistakenly picking up on your voice while in conversation. (There are "Do Not Disturb" controls too.)
It may or may not help to steer clear of common sources of interference as much as possible: eg: power cables, microwaves, fluorescent lights, wireless video cameras and cordless phones.
There is an Audicus support center online:
https://www.audicus.com/support-center/
Apple provides an Accessibility Support Team:
You may want to try reaching out for their help with Voice Control:
See: How to contact Apple for help with accessibility features - Apple Support
All the best :-)