I gotta be honest, I haven’t used a dedicated sound card since the Vista/7 era when EAX stopped being a thing and onboard sound could handle 5.1 output just fine. The last one I had was a SoundBlaster Audigy.
These days the main uses for dedicated sound interfaces are for when you need something like XLR in/out and then you’ll probably go with something USB.
I wouldn’t bet on it. The Wi-Fi/Bluetooth module in there doesn’t seem to have a standard form factor so even if you can slot in a standard module you might not be able to connect the antenna wires. Also, this MBP came out just around the same time as M.2 so you’ll probably have to go for an older mPCIe module.
A USB adapter is the far safer bet.