Loading assets from specific folder on mobile

[FroGlenn]

Hi. I'm working on a game with 450MB with max compression (HD images using JPG medium or WEBP compression). Its pretty big (4.000 images and more than 2mi characters). The game is focused on Android market and its doing ok, but I want to do something a lot of big games are doing right now on mobile.

I want to make an APK with just the first chapter of the game (50MB) and then download assets from a server on demand as the player progress through the game.

I'm using a lot of mobile functions that I customized on my renpy game, like consumable purchases, cloud functions, database and cloud storage for saving/loading save files for ppl who want to uninstall and reinstall later. Firebase is great for all of that.

To achieve this new functionality, I will put the game assets on a bucket in Firebase and download it to the data folder (same location where Renpy save the save files) on demand. This way, I can keep the game light on download and the player will have all the content in the right moment. This I can do.

What I need to know is: how can I make my renpy game load assets from this custom folder outside the /game/ folder?

Please, can someone tell me a good way to handle this? Which function I need to use? Im banging my head over this for months now and I think I'm close, but I dont know Python and Renpy enough to do this step by myself. Thank you all very much.