(14-07-2021, 07:27 PM)lilfroggy I have a teclast p20hd (unisoc) android 10. Is it possible to downgrade to android 9 with gsi rom and flash twrp?
if your goal is to downgrade to android 9 just to get twrp then i'm afraid twrp still won't work as the kernel version is still android 10
if your goal is to downgrade to android 9 for the sake of experimenting, then sure you can try it out and let us know the results