[Android Q&A, Help & Troubleshooting] x0xb0x:
I did it!

For the brave sould deciding to go down this rabbit hole mess, please note I am on crDroid 7.x on both my devices. It could be a totally different guide for your case due to how the Android build and ART preoptimization work for each different ROM.

Initially had totally forgotten about the convoluted ART caching & preoptimization but @rocker00 provided the valuable hint: to delete boot-framework.art & oat as well as framework.vdex after placing in the modded framework.jar. Thanks so much matey!

Here I did not only neuter the spoof I completely removed it from framework. Both my phones are on Andrdoid 11 crDroid 7.x. This was performed on a POCO F1 first.

1) I first got a general look at the Github source code where PixelPropsUtils was used and it is literally 2-3 calls: https://github.com/search?q=repo:crdroidandroid/android_frameworks_base+PixelPropsUtils&type=code

2) Copied system/framework.jar to a (phone's) Downloads/work/ directory so as to edit it. All PixelPropsUtils calls (in my case) reside in this framework.jar. Unfortunately as also noted by @rocker00, APKtool, smali, baksmali in all attempts FAIL to produce a bootable jar.

3) Hence as suggested I Installed MT manager apk from the official Chinese page. For the interested members , google it and you will find the correct one. I managed to get the correct APK. After installing it, I ONLY gave it filesystem permission and NO root NO network. I just wanted to edit the local jar and nothing else.

4) Opened the framework.jar inside it. In my chase it contained four classes.dex files with 2 or 3 of them containing PixelPropsUtils calls.

5) Opened classed.dex with the MT tool's DEX editor plus. What an amazing tool... It offered me to open all three other remaining classes.dex files and so I did.

6) Performed a smali search for PixelPropsUtils. The results were aligned with the Github source code so I was on a good path.

7) In smali I removed each and every call to PixelPropsUtils along with the '.line' directive above it.

8) After all calls were removed and I was sure from the Github Java source that PixelPropsUtils is not used anywhere else I also deleted the PixelPropUtils class itself.

9) Subsequent smali searches for PixelPropsUtils in MT manager should return NO results.

10) SAVED the modded jar. MT manager backs up your old one into framework.bak

11) RE-ENABLED the Chimera service and all the other ones I had disabled with pm disable.

11) Then deleted my Google account and cleared cache and data for every Google program, GMS framework , everything.

12) THEN ... THE MOST IMPORTANT PART:

Booted into TWRP and mounted system/

Deleted all ART preoptimization files for framework:

system/framework/arm/framework.vdex
system/framework/arm/boot-framework.oat
system/framework/arm/boot-framework.art
system/framework/arm64/boot-framework.oat
system/framework/arm64/boot-framework.art

Replaced framework.jar with modified one with correct permissions.

Cleared Dalvik and cache.

13) BOOTED SUCCESFULLY !!! YEAH !!! adb logcat on boot briefly complains about framework.jar not being zipaligned, but DON'T try zipaligning it after all the MT manager tool procedure. It makes your framework unbootable.

14) Re-added my Google account. After this Chrome was refusing to start but after removing/reinstalling all was OK.

It seems that everything works.

My phone is now recognized by Play Store as Xiaomi Poco F1. No more SystemUpdate draining my battery and Google services going berzerk. What a relief and at the same moment ... WHAT A HORRBILE MESS.

I really cannot understand why our beloved ROM developers have skipped through this issue. So many of us rarely change rom if it works so why get through all this pain just for SafetyNet? Or even worse, unlimited GDrive photos? LineageOS got it right from the start. NO SPOOFING.

As for UNOFICIALL Lineageos builds: Whenever you see on the Changelog that they "Fixed SafetyNet" it means that the rom is spoofed and sooner or later all H3LL will break loose.

As for all all workarounds discussed here only:

* Only pm disable Chimera works and nothing else.

* ONLY REMOVING THE SPOOF SOLVES THE ISSUE fully

* You can re-enable the Google services that you did "pm disable" on without them going crazy now. You do not have a Pixel-spoofed device anymore right?

* Discussions about security update versions , the rom is old or not etc. etc. are pointless. If Google thinks you have a Pixel it will try to OTA regardless of your wishes.

After all this painful work:

With full Google sync, Find my device and all other trash turned on (observation purposes) I am getting NO MORE logcat Exceptions, UpdateService going berzerk and the relevant bullsh1t. Crazy good battery life for more than 4 days.

Constantly observing top -H in termux (root) for process behavior. Everything in my ROM is outdated and SafetNet fails but I don't care. Use Magisk Hide for the problematic apps or find other alternatives for banking.

I just wanted a functional daily device and now I have one. When it gets older I can continue using it with a perfectly fine ROM. Without Google burning my battery. Or maybe degoogle it and make it something lse.

@rocker00 is right.

* Security revisions, ROM old or not etc ... all this doesn't matter. If Google thinks you have a Pixel then you WILL get these nightmarish issues.

* THERE is no workaround other that disabling Chimera.

* There is NO REAL FIX other than FULLY de-spoofing.

It is what it is.