Easy way to deploy iOS for Dev/Stage/Prod Environments

All Developers :
Did anyone found out a way easy way to manage iOS app in three different environments Dev/Stage/Prod?
Considering the following pain points, looking for better options available -

1. Code Signing using Distribution Profiles (having UDID's) for test devices from testers
   1. Retrictions of 100 iPhones can be registered and Apple not allowing reseting the device list on need basis.
   2. Even Apple allowed to Reset the device list, there could be organization running different development teams which easily have 100+ iPhone test devices
2. Testers, Product Owners require all three environments installed at the same time

   Yes, its too much work to have individual bundle identifier for each environment. Just imagin when you have Siri Kit and Apple Watch app

3. Some times there is need that you have to invite some organizational person to review/test your app
4. Crashlytics being going away starting April 01 and iOS users may not have gmail id to happily migrate to Firebase Crashlytics
5. Any many more......

Please let me know in case any one found the so far a way to achieve deployment of the apps.
One possibility I could think of is extending Test Flight features where is looking for some help from Apple. Have filed the Feedback ticket -
•Test Flight Feature RequestFeedback - FB7552354Developer Tools1/26/20Open