In this specific case, throwing /system_ext/priv-app/PriLauncher3QuickStep/PriLauncher3QuickStep.apk at VirusTotal would light it up.
But as I found, ESET won’t care about system files.
Sophos’ Intercept X did find it, but I had to enable scanning of system files in settings. Though I am not sure how reliable they are for AV.
Oh, and if it finds something, it will block you from opening that app. In this case, that being main part of the UI, I couldn’t access recent apps and homescreen. So for the chance it flags Settings, it would probably be good to enable ADB in advance (and trust your computer).