Profiles are a standard Android feature, nothing special to Xiaomi. GrapheneOS even extends and improves them in a lot of ways.
It's just not possible to hide them in a good way that would faze knowledgeable people or software.
not accessible just by typing another pin on stock Android though.
Ok so what you're saying is Android doesn't have this feature. Xioami does. Type in a different pin and access a second space. Not the same as profiles, obviously