If you want to check beforehand (or afterwards), if your ROM supports Signature Spoofing, use this [tool](https://f-droid.org/de/packages/lanchon.sigspoof.checker/).
If your `/system/framework/services.jar` file contains the file `classes.dex`, you can skip deodexing and start patching right-away, else following theese instructions.
VdexExtractor will create CompatDex for Android 9.0 (more precisely VDEX 019 files) instead of DEX. Theese CDEX files can only be manually converted to DEX on a GNU/Linux or MacOS PC, see [this instructions](https://github.com/anestisb/vdexExtractor#compact-dex-converter).
If you can see `/system/framework/oat/[arch]/services.vdex`, where [arch] is the device architecture (arm, arm64, x86 or x86_64), you should follow theese instructions.
if it's properly been created rename it to classes.dex and add it to `services.jar`, if there are additional files like services.apk_classes2.dex, rename them to classes2.dex and so on and add them to services.jar like:
If you can see `/system/framework/oat/[arch]/services.odex`, where [arch] is the device architecture (arm, arm64, x86 or x86_64), you should follow theese instructions.