I figured out how to use ReVanced CLI so that you can patch APK's on your computer. I'll write up a guide on how to patch Google's YouTube app to make it ReVanced and run rootless. If you know how to root your phone you probably are already capable of following the instructions for the rooted variant anyway.
You will need:
The patching utility from GitHub
This specific version of JDK, preferably as a .zip (according to the instructions on the revanced-cli repo you need a x86/x86_64 host)
The newest bundle of patches (you will also need to use the readme during the process)
The newest integrations
You also cannot be a nigger because you will have to use a command line.
After you've got all this, it will be the easiest to unzip the JDK somewhere, and then throw your patching utility, patches, integrations and the APK you want to patch into the bin folder.
As for which APK you should get, look at the patches repo. It has APK package names listed, as well as the patches supported by them and the newest version that they're meant for. As of writing this comment the newest supported version of YouTube is 18.05.40. Go to apkmirror.com, find the newest version, and download the newest APK (not bundle).
Important thing to note: you will have to rename the .apk file to the same name present on the patches readme, or else the patcher won't know which patches it needs to apply and instead it will apply all the possible patches for all the possible apps.
At this point, in the bin folder of your unzipped JDK, you should have:
revanced-cli.apk
revanced-patches.jar
revanced-integrations.apk
com.google.android.youtube.apk
So now you start the command line in this location, and enter the following command:
java -jar revanced-cli.jar -a com.google.android.youtube.apk -c -o revanced.apk -b revanced-patches.jar -m revanced-integrations.apk
It will run the Java exectuable, load the ReVanced patcher, and it will parse the name of the APK you want to patch, clean the cache, parse the output name of the patched APK, parse the file containing patches, and it will also merge the ReVanced Integrations APK which is required for a bunch of patches.
After hitting Enter, you should see a whole bunch of INFO: lines popping up. First about reading dex files, decoding AndroidManifest.xml, skipping some patches that are excluded by default, merging integrations APK, and then a bunch of "succeeded" messages regarding specific patches.
By the end of the process you should see zero errors and in the same folder as the unpatched APK, you should see the revanced.apk file, that's your ReVanced app. Copy that over to your phone, install it and you're done.
Now, sure, this process is way more convoluted than just using the ReVanced Manager app, but keep in mind that the app runs on your phone's CPU which is multiple times slower than your desktop, or even laptop CPU, so via the CLI utility you will patch it faster.
EDIT: Took me way too long but I made a simplified script for batch patching. Note that it's just the script, and you will need to follow the instructions to actually set up all the software needed for patching. After that it should be very simple to use.