Driver problems (no audio) on Windows 10 (installed without Boot Camp Assistant)

Hello.

I've had Windows 7 installed through Boot Camp Assistant running fine for years now, but decided to make a clean upgrade to Windows 10 today - using a new SSD, specifically.

On my Mac side, running Mojave*, I downloaded the latest Windows 10 image (November 2019) and opened up Boot Camp Assistant, but I ran into problems straight after that: I kept getting an error about the failed download of the Windows software, even though I was attempting to install the whole OS and not just to download the software, and I couldn't make sense of it in any way.

After exhausting several alternatives, I tried creating a bootable Windows installer and eventually managed to do it on an external drive formatted to ExFAT (I wasn't able to use other formats due to the Windows .iso being larger than 4GB); I installed the OS and then all the BootCamp Windows software (through the specific BootCamp Assistant option, which worked fine for this) and it all seemed to be working fine, until I noticed that the Apple drivers weren't working as they should.

Specifically:

• I get no functions related to the F1 to F12 keys, so no keyboard backlight management, no screen brightness option, etc.
• I have a "No Audio Output Device is installed" error that gives me no audio whatsoever.

Everything else seems to be working fine, but I'm not 100% sure since I've been focusing on these problems. I tried everything to fix this: reinstalling the audio drivers specifically, reinstalling the BootCamp drivers (through the setup exe, through the single exe's, multiple times), removing the drivers, using Windows Update, using Apple Software Update, using various software specifically to download and update drivers, installing other audio drivers (Realtek, Cirrus), updating through Device Manager, but nothing works.

In Device Manager, I have an exclamation point next to "Sensors > Light Sensor" and "System Devices > High Definition Audio Controller".

To clarify:

• My main OS, macOS Mojave, is installed on an SSD, on its own. Windows 10 is installed on a separate SSD, on its own.
• *I'm using Mojave because Catalina was giving me problems with the lacking compatibility of certain 32bit apps that I couldn't go without; so I downgraded (clean install).
• On boot, Windows 10 shows up as "EFI Boot", not sure if that's relevant.
• I have a mid-2012 13" MacBook Pro.

I'm at my wits' end. I'd really, truly appreciate some help with this. Thank you.