mar2112 Aurora is just a client app for the Google Play Store. So if you download the most recent version of an app through Aurora it should be exactly the same version as installed through sandboxed Google Play Store app. I wrote 'most recent' because with Aurora app you have the possibility to search for and install older versions.
So you could also do the 'safer' way: install the app through Play Store app in 2nd profile and after that install it on owner via Aurora. Because of the system's automatic signature check it would only be possible to install that app via Aurora if it fits the signature of the already via 2nd profile installed app. Or maybe it's just a check and making the app available in owner - because the app is already installed system wide I don't know if it would be reinstalled or just activated for that profile.
So yeah, these options are already known and a couple of users use it these ways. But many users want to avoid using Aurora for different reasons. I don't' want to repeat the concerns and pro and contra of using Aurora vs. sandboxed Google Play, because it's discussed a lot on this forum. I'd just love to use the installation and update process in the described way without Aurora and without installed Play Services in owner profile. Because the app installed by 2nd user is already visible in owner, only the ability to activate it for the owner is missing. That should be technically possible.