Several audio issues

[mtfzoe]

Hello!
I looked at other posts and found kind of solutions but I was hoping for one a bit more permanent.
For starters I just got a raspberry pi zero W and set it up inside of a gpi case 2W in order to emulate old games on a handheld system. I got everything working but it has audio issues.

The first issue is the error VolumeControl::init() - Failed to find mixer elements!
I know this is a common issue but I have been struggling to get rid of the error
The second issue is that it appears retropie is only allowing for headphones output. There is no option for hdmi, 3.5mm, speaker, etc in the raspi-config menu. It does show those options in the main menu sound settings though.
The third issue is the audio resets to 0% when leaving the main menu. I found a solution for headphones by doing amixer sset Headphone 100% but it isn't working for the other sound options.
And the last issue (I think) is that the built in speakers for the gpi case 2w don't play audio, except during boot up. I haven't gotten any results here and I would prefer the built in speakers to be my main audio source.
Any help would be appreciated! Thank you!

Edit: Also I just remembered another issue. The headphones when plugged in only play in the left ear not the right.
Edit: The pi model is a Raspberry Pi Zero W
The PSU is a rechargeable lithium battery that is new and works
I used retropie 4.8, built from the official imager
As for usb devices it is the GPI Case 2W which is a handheld gameboy inspired emulator with a screen buttons and speaker

[windg]

Please add more info: https://retropie.org.uk/forum/topic/3/read-this-first