i think is just a waste of time trying to get supermod8 working.
If you flashed twrp, try using twrp and delete what you don't need. As Emilson wrote..Thank you for your reply, i will check the root procedure.
Which TWRP you used? And im also interested in the two zips for optimizing system performance, you got any links for me?
EDIT: Rooting does not work, i did it like you described (Preserve AVB 2.0/dm-verity and Patch vbmeta in boot image were not picked in the options), after flashing the new boot.img magisk itselfs says installed 25.2 and an app like link2sd or mixplorer accesses root but when i try to delete an app or rename a system file it says no file deleted, no file renamed.
When open Magisk it says "Abnormal State A "su" binary not form Magisk has been detected. Please remove any competing root solution and/or reinstall Magisk"