Migrating specific users from app written in ionic to new version written in React Native without MDM

We have an existing version of a mobile app in Appstore. This app was written in ionic version 2.2, more than 4 years back.

To improve user experience and to add helpful features, we re-wrote the app in React Native. We are planning to release this new version in 2024.

We want a recommendation on how to release the new version in a controlled way to selected few users only. We will have a specific target audience for the new version, not random sampling (so, can't use phased release option). User selection will be driven by a database.

Constraints as follows. Old app is frozen. It's very difficult to change anything in it. We do not have MDM. It’s a public facing app. We should be able to control who get’s which version of the app. We should be able to roll back to the old app if needed.

We are trying to bundle both apps in a container app which will route the user to the old or new version of the app (within the same bundle). Have anyone done anything like this before? If not, do you see any technical difficulties with the approach either during coding or during Appstore review?