Greetings,
the solution is quite simple and 100% possible if the following criteria is met:
1.) all the 50k meshes should not be different, there should be at least 10-20 meshes that are repeated again and again to make a sum of 50k.( if there are slight variations for each 50k meshes, then also its possible).(PS: can only be estimated by chat)
2.) in point 3.) if you are referring the "APP" to as final built package (hopefully for windows), then its impossible ( I am considering the fact that you are suggesting something similar to anti cheat splash screen when opening a multiplayer steam app).
Now the major issue is, due to lack of communication, I Suggest you personally contact me just and just so that I can have a idea what stuff you are working upon, putting 50k meshes in a single level/map is not a joke, and I am not sure if you are trolling.
anyways I love the fact the fact that you use ; instead of period ".".
Also please see, the amount and deadline are not final since I have not understood the concept 100%.
thank you for reading till end
regards.