is it turned on in the launcher, press and hold your finger on screen(not on a icon), go to more, should be 4th option from top called -1 screen. thats how it is on my Mi11 Ultra.
Dude, I have a Mi 11 Ultra as well, not sure what you are referring to with issues. cxan you explain in better detail so someone can help.
You should not have to remove the pin. Maybe you have an older TWRP?
As for the second question after there is a working TWRP, they (xiaomi.eu) usually...