Take a look at the old method Google Drive....Did you do this on the OnePlus 9 Pro?
I am assuming you installed the OnePlus dialer, right? If so, where did you get it?
Hey everyone!! Greetings from my side. We were trying hard to get 100% working oneplus dialer and messaging app in oneplus 8t. and Yes, We have successfully done it. I am very happy to share the guide with you all :) WITHOUT ANY ROOT METHOD...