Unable to update AirPods Pro 2 to the lastest firmware

See this about AirPod Firmware updates. About firmware updates for AirPods - Apple Support You cannot force an update to the Firmware. Hearing Aids and AirPods Pro are two different things, paired differently. See this about using AirPods Pro hearing aid feature. Use the Hearing Aid feature on your AirPods Pro 2 - Apple Support

I have my MFi hearing aids paired to my iPhone and also have setup hearing aid feature on my AirPods Pro.

I suspect that the hearing aids were, because I've had them longer, and were paired through Accessibility and the Smart 3D app, which is for Resound hearing aids. The AirPods Pro are connected via Bluetooth, so it is two different setups. You should eventually get the latest firmware for the AirPods if you have them connected and used them. It explains how to give them a chance to update the firmware in the link I gave you. You said the hearing aids you have are MFi, do they pair through Accessibility.

Just for the heck of it, I put in my right hearing aid and then put in my left AirPods Pro. Then I went into the AirPods in Settings and turned on Hearing Aid and both of them are working. I would try turning off the hearing aids, then pair your AirPods Pro to the iPhone and let them sit. I believe they have to be charging. Then check after a bit to see if they have updated. Once they update you can take the hearing test and set them up to be used. Then you can turn that feature on or off.

Where did you buy your AirPods? The fake one could not upgrade the firmware.

I purchased mine at an Apple Store.