Is it possible to get an app for internal employees in the AppStore? We're developing an app for internal employees for easy communication. Now we want to remove all potential barriers for our employees (1500+) to install the app.
Therefore we would like to host the app within the AppStore - employees can then download it like they are normally used to download other apps.
Of course there will be a login screen in advance to make sure that only employees see the right information.
The app got rejected with the following:

Guideline 3.2 - Business
We found that your app is an in-house app, intended for employees or
members of your organization. As such, it is not appropriate for the
App Store.
For information on distributing proprietary, in-house apps, please
refer to the Apple Developer Enterprise Program.

We tried to use the Enterprise path, but when the employee downloads the app you're getting to this part:
https://support.apple.com/en-vn/HT204460
We see the Manually install and trust an enterprise app as a big barrier for getting our employees to download the app. Is there any way to solve this?
Is there an 'AppStore' for internal business apps?
How are huge companies with 15.000+ users handling this when there is a Bring your Own Device policy?
First, it is not possible for an organisation to get an internal app into Apple's App Store.

Most large organisations manage both corporate and BYOD devices using a Mobile Device Management (MDM) system.

My organisation uses AirWatch but others include JAMF, Microsoft InTune, SimpleMDM and Meraki.

An MDM can either deliver the app automatically or provide some form of self-service for internal apps.

All of the MDMs listed above have an associated cost. There are some open source MDMs available but at the moment they all seem more focussed on Mac management than iOS.