I don't expect anybody is trying to jailbreak phones that have an official way to unlock them, even if it is very annoying.

Xiaomi devices are a bit annoying to unlock but you should use the official way. I've got a xiaomi device and unlocked it. So first you need to be patient maybe it's not going to work for the first time so try to unlock it and if it doesn't work just wait a couple of weeks... And you should maybe ask a friend or family member to take their Sim card only to log into a xiaomi account and allow OEM unlocking. You could try an other method but when there is an official way (annoying but official) you should use it, safest and "easiest" way.

I agree with the other comment. If it is possible, it's most likely the folks on XDA will know

Try searching this " rom xda developers"

Your phone has a snapdragon which is very popular chip to make ROM for but generally hard to unlock unofficially -not impossible though it's possible there is a workaround by now for your specific chip - on the flip side mediatek devices are less popular due to them refusing to provide the source code but to their partners. however they are well-known to be easy to unofficially unlock due to some vulnerability -in the bootloader- that they refuse to patch.

I did a leap of faith and I unlocked my phone unofficially (mediatek) but if you decide to flip that coin think hard about it and make sure you are well informed (like using your specific phone code name instead of brand name ex: instead of redmi 9 say "lancelot")

You need to use the official way of unlocking (official Windows app and phone number). There are no other ways of unlocking I'm familiar with. I believe in the past you could unlock it via EDL testpoint but now it somehow only makes the device think it's unlocked but you still can't install anything. Buy a Pixel for easy unlocking.

I know it's not the answer you're looking for but IMO you should consider selling the device and getting a (perhaps used, depending on personal situation) Pixel a-series device instead. If you're using some brute force method, you may be ending up with a bricked device.

1. Don't use hacky unlocks if there's an official way. The best case scenario is it becomes a headache and isn't reliable; ghe worst case is that it bricks your phone or installs malware in the bootloader

2. All I could find looking for custom ROMs for your phone was XDA users shrugging their shoulders and unverified downloads from very shady websites/githubs. I'd suggest getting the most out of this phone you can before selling it and getting one you know works with the OS you want

Do it the official way. SIM cards are cheap.