graphik OK. There you go. For a staged install, you first create a session:
pm install-create -i com.android.vending /data/local/tmp/base.apk
As output from this command you'll get an identifier, which has to be referenced thereafter. In the examples below it's 12345678.
Then you add the APKs one by one. For example:
pm install-write -S `stat -c %s /data/local/tmp/base.apk` 12345678 0 /data/local/tmp/base.apk
pm install-write -S `stat -c %s /data/local/tmp/split_config.arm64_v8a.apk` 12345678 1 /data/local/tmp/split_config.arm64_v8a.apk
pm install-write -S `stat -c %s /data/local/tmp/split_config.xxhdpi.apk` 12345678 2 /data/local/tmp/split_config.xxhdpi.apk
And so on (if there are more). Note that for each APK you have to include the file size as a parameter, which I am sort-of automating here with stat(1). The following parameters are the session identifier mentioned above, and a counter incremented for every subsequent file.
Once all the files have been added, commit the result with:
pm install-commit 12345678
This is an example, assuming you have all the APKs waiting in /data/local/tmp, for example copied with adb push. Or, if you have the app already installed, with sufficient privileges you could "borrow" these files that are already on your device with something like:
cp `find /data/app/ -path \*com.example.app\*.apk` /data/local/tmp/
Just for completeness, since it would require superuser privileges not available to us, alternatively to all of the above, you could simply edit the installation source in place, without having to reinstall the app at all:
sed -i -e "/com\.example\.app/s/com\.aurora\.store/com\.android\.vending/g" /data/system/packages.xml
Although you'd have to stop the runtime while doing this with stop from adb shell.
Note: these are just examples intended as an illustration and a proof of concept. Please do not attempt to run them without understanding what they do first.