I finally made it to Big Sur after more than 30 hours of bathing in blood and sweat fiddling around to achieve it.
1. What I thought to be "installer crashing" at 12 minutes mark turns to be a non issue. I found this out when I was about to give up and decided to go back to Catalina. While I was trying to install Catalina using OpenCore 0.6.3 (the same one I used to install Big Sur), I had the same issue. However, in Catalina, the 2nd reboot succeeded and the installer continued its progress. There's a few reboot after that but that's normal since the progress bar keeps going to its end. This made me realized that the problem with Big Sur is exactly at when it tries to reboot the installer for the first time.
2. After Catalina got installed, I try to do a direct upgrade to Big Sur from within Catalina. The installation went well since its not crashing (or so I thought). But when it tries to go for its first reboot to finish the installation, the same thing happen - I got into a boot loop of misery.
3. Luckily, I have a real Macbook Pro (mid 2014). I grabbed my external HDD enclosure, connect my SSD to it and start installing Big Sur to my SSD (which is now connected externally via that HDD enclosure) by clicking on the downloaded Install macOS Big Sur.app. The installation went fine. It even survive the reboots.
4. After installation finished, I booted the external SSD using my Macbook Pro and continue creating user account. I didn't login my iCloud yet at this point though.
5. After logging in to the desktop, I mount the EFI partition and copy my EFI folder that I used to install Catalina previously. Then, I shut it down and detach the SDD from my external enclosure. Then, I connect back my SSD via SATA to my PC.
6. Boom! Big Sur booted successfully.
1. Everything including iCloud drive sync, audio, sleep, ethernet, wifi, bluetooth, airdrop etc. excluding:
What does not work:
1. DRM works partially. VDA decoder works but Netflix won't allow me to watch the movie. The short trailer works though. I don't really care about this as I usually watch Netflix using a custom extension made for Microsoft Edge (to get 1080p).
2. Emulated NVRAM. Since this doesn't affect anything like iMessage etc., I also don't care about this.
Using this method might not be the best experience. I might have to reattach my SSD back to my Macbook externally to apply any macOS update in the future if there's any . But while quite cumbersome, it's manageable. Hope OpenCore will fix this before the next macOS update.
EFI folder that I used attached below.