Hi! I almost forgot to say, so I'm doing it before forgetting for good:
You're not the first to hit Android limits: I've seen at least 2 Itch.io games having the same issue, and I'm pleased to say they found a way to get around it.
The first solution involved using Joiplay, which I wouldn't recommend because it is a bit harder to run and since it is emulated it can present incompatibility or performance problems.
The second is far better, they managed to split the game in 2 files: an apk with the game code and a file that contains all the resources of the game. They even managed to require the resource file to be put in a Documents' sub-folder, thus avoiding file managers and permission issues.
As for how exactly it works, I cannot say much since I'm not developing on either RenPy or Andoid. I'm just reporting other's discoveries, I hope it will help a bit (feel free to ask which games I'm talking about, I don't want to make unwanted advertising).