Google Play Store: the best way to install the Android application on 500 tablets?

We have 500 tablets that need to come out with our pre-installed Android application. According to our experience so far, the only way to install the applications is to create a new Google account, by logging into the Play Store and installing the application. The problem with this method is that it consumes a lot of time and creates unwanted accounts that I'm sure Google does not want.

The obvious alternative is to manually load the application with the APK file manually, but the disadvantage of this is that we want to be able to update the application later. I understand that if we load the application on the one hand we can not update it automatically.

We are already using Ionic Pro, which has live implementation that handles most of the small updates, but can not implement live updates that imply updates for native / cordova add-ons.

Since both methods have drawbacks, I hope there is another way. I am curious to know how educational institutions can preload applications in classroom tablets that are updated without an account started in the Play Store.

To be clear, and to avoid duplication of other similar questions, what I'm really looking for is to use Google Play Store to get updates, not to ignore it, but without having a unique Google account per tablet.