i have the european version of the phone with official xiaomi global rom and i replaced the single tray with dual tray and i installed xiaomi.eu stable
works 5g+4g at the same time
they do this with every phone i have( monet and andromeda) , i think switching to other brands, they focus on flagships and low end but not on midrange
twrp for 5g version is not yet available afaik...
you can download official xiaomi rom for 5g version at xiaomi website in 2 versions -global and eea(europe)