Extracting data from FGO on Remix OS

Basically what the title says.

I have installed FGO - the NA server - on my unrooted instance of Remix OS, when there was the "Magical Girl Cruise - Prisma Codes" event. I liked some BGMs a lot (especially the one used in the event map) and I haven't updated the APK yet since the event ended, so I considered the idea of extracting some assets from the game, if possible.
I know FGO is very well-encrypted in some cases, so I wonder if they can be extracted easily.

Also I re-rooted Remix OS after the event ended because I wanted to search the files myself.

Thanks in advance, this really is a handsome forum

Prisma Codes OST is from Prisma anime
look up official OST for Prisma anime and tracks used in fgo should be among them