Disappointing stereo

I can't believe how bad the stereo sound is on my 2023 Envision Essence. Without adjusting the fade settings 75% of the sound you hear is from the center dash speaker. Can barely hear the side dash speakers and virtually nothing from the back seat. Adjusting the fade to get more sound out of the rear speakers doesn't help as they're poor quality with limited range. I was so sure the stereo was defective I went back to the dealer and sat in an identical model on the lot with the sales manager. But it had the identical poor sound. The sales manager was surprised as well. I wasn't expecting to have Bose quality sound but I didn't think it would sound like A.M radios from 30 years ago. Not in a $42K Buick.

I've looked at ways to upgrade but I see a lot of comments about interference from the ANC. Adding a sub woofer doesn't seem to be an option due to the ANC. The stock stereo has 7 speakers where the Bose system has 9. The good news is my Envision has the speaker grills already in place for the two missing tweeter speakers in the rear cargo area. Crutchfield says the replacement size for these locations are 2 3/4".

Adding a pair of speakers to the rear cargo area and upgrading the four in the front and rear doors plus an amp could make it sound a lot better. Anyone done something similar?