Wow, this has been an effort. All I wanted to do was plug in my Batocera boot drive, add some files to it, and move on.
The quick way to do it?
- Boot your Batocera.Linux USB drive on ANY machine (it won't erase the local drive unless you tell it to)
 - Find out where on the network it is in File Explorer (usually \\batocera\Share)
 - Now you can browse it and drop files to it.
 
Now....If you are like me and you have a card full of micro SD chips (dust motes I call them) and you have no idea what was installed on each of them. Then you have this problem.
- I don't know what's on there
 - I don't want to boot it up
 - I don't even know if this is a Raspberry Pi boot chip or x86
 - When I plug it into windows I get one drive that looks vaguely familiar Some boot files.
 - I can't see the other drive (cause it's linux and Microsoft doesn't want to talk to Linux)
 
You will need to do a few things.
- Install WSL (Windows System for Linux) on your machine.
 - That's great, but when you do the whole "Mount a Linux Drive for Windows"
 - Windows 10 now lets you mount Linux ext4 filesystems in WSL 2 (bleepingcomputer.com)
 - wmic diskdrive list brief
 - wsl --mount [DiskPath]
 - wsl --mount \\.\PHYSICALDRIVE0
 - It fails. Because WSL Does not support mounting USB Drives at all.
 - So now you have to install an additional utility
 - Connect USB devices | Microsoft Learn
 
After that, you should be able to mount and see the Linux partitions and do something useful with it. It's a pain in the butt, but until Microsoft learns to play nice with Linux, that is where you're at.
Oh, the other "simple" way?
- Grab an old computer and stick Ubuntu with a desktop on it.
 - Download Ubuntu Desktop | Download | Ubuntu
 
You weren't using that old Core2 Duo machine for anything anyway.