I'd say stay away from it! From what I understand it mostly depends on what OS is running on the phone.
Phones on their old Xiaomi OS can be unlocked reliably. You have to register an account, wait 30 days, and use the unlock app on a Windows computer. It's annoying but doable. But, the current Xiaomi HyperOS is where the insanity starts. It's pretty much impossible with arbitrary limits of global unlocks per day. The app constantly telling you to try again the next day and stupid stuff like that.
I've had that phone sitting in a drawer for a month or so now. It's just not worth it. And I'm not going to put anything personal on their shipped OS. When system apps come with popup ads to install dodgy crypto apps I'm not going to trust it.