Advice/issues adding DSP/Amp to the Bose system

I have a 2023 Elantra N and previously had 12 inch Sony ES dual sealed subs with a JD 1000/1 amp installed by a shop along with replacing the front with component 2 piece sony ES speakers. I also replaced center with Dayton 3” speaker after watching the N Prform videos. I messed with the EQ which helped, but I am still not quite satisfied with the sound, it does not sound as good as my home sound system, and I wonder if it is primarily a tuning problem at this point which got me interested in DSP.
So I looked into adding an aftermarket amp which I heard could make a significant difference and AI pushed me towards an LLJ customs loopback wiring harness to address the Bose system. Anyways that was a wash because the harness is only for specific car makes, no Hyundai option. I still have a kicker 47key 200.4 that I got because of the auto DSP, but now that I can’t use the loopback harness I am not sure what to do.
I am considering three options. Give up and use my current system and try to sell my kicker key amp, or splice into the Bose output signal like in the N Prform videos, or use Metra AXDSPX-HK5and tap into the preamp signal.
I don’t mind spending some money if I am going to get good, noticeable results. I think I have good ears, but I do not have audiophile ears. I would gladly take 80 percent of the gains at a budget price.
Which route should I take?

1. The direct wiring route like N Prform. In my mind this is the budget option I would do myself and would very strongly consider this if it will work well with my kicker 200.4 amp. With 4 channels, I think I should use biamp mode and focus on giving all 4 to the front woofers and tweeters. If I did that I could leave the center and rears connected to the stock Bose signal, but I am afraid it might cause some balancing problems and maybe I should just drop the center and rear channels. I could also give two channels to the front if the signal is split so with passive crossovers and the other two channels to the rear.

2. Using The Metra HK5 sounds like the cleanest way to get this done, but also the most expensive and I would have to pay for professional installation. And at this point would probably get a full 6-8 channel amp/DSP with higher RMS. I will consider this if results are great and the previous option is bad.

3. Give up, sell key kicker on marketplace and enjoy what I have, it is decent.

Additional questions
4. Bose is an 8 piece system but only 6 channels? The front doors use a single channel from the amp and use passive crossover? If they use a passive crossover over and a full signal why did N Prform in one of his videos talk about having to sum up the front and rear channels to get a full range signal?

5. Has anyone had fault codes or chimes or navigation prompts with disconnecting center or rear speakers? I saw at least one person on the forums say they disconnected them with no issue, but AI is trying to convince me it is an issue.