Mr. Fusion is a tiny, custom Linux distribution designed to run on the DE10-Nano and install MiSTer.
When you put this SD card into your DE10-nano and start it up, it will expand the card to its full capacity and install a basic MiSTer setup. This will be familiar to anyone who’s worked with a Raspberry Pi before.
From there, using the built-in scripts, you can configure WiFi (or use ethernet out of the box) and run the standard MiSTer Updater script to get an up to date MiSTer installation.
You can provide custom WiFi and Samba configuration which Mr. Fusion will install alongside the basic MiSTer setup.
https://github.com/MiSTer-devel/mr-fusion for further detailed instructions.