I have tried multiple times, just reboot and breaks it. Even after working on A12 then upgrade to A13 it breaks it.
This Module doesn't work on OOS 13 Stable, only OOS 13 Open Beta 2 and older.
You didn't have to reset your OnePlus 8 Pro with MSM, you just had to power down your 8 Pro, then turn it on and hold the volume down button as soon as you see the OnePlus logo, from there it boots into safe mode and disables all Magisk Modules, from there reboot once more and enable all your modules except Pixelify.
Certain Pixelify features should still work with Pixelify Magisk Module disabled, on my OnePlus 9 Pro running OOS 13 and Pixelify disabled I still get Next Generation Assistant, Hold for me, Call screening, Direct my call, call recording (I live in the U.S. where this is disabled), Live Translate, and Live Captions (9 Pro came with this out of the box).
I haven't tested everything, I excluded installing Pixel launcher through Pixelify because but I found out I get better compatibility with
Pixel Launcher Mods (icon changer for Pixel Launcher, doesn't work if I install Pixel Launcher through Pixelify) if I download the latest Pixel Launcher APK, install it, then use
Quickswitch Magisk Module to change my recents provider from OnePlus System launcher to Pixel Launcher, then set my default launcher as Pixel Launcher... confusing, so much launcher lol.
Check out this video and 2 screenshots, I can't test more on video without doxing myself lol.