So, not that anyone has asked, but in case anyone was wondering, the Linux binary version of A7800 works fine on the Steam Deck without any issues. Just don't try to install it to /usr/local because of the read-only file system, but it runs fine from a home directory. I made an executable script in the a7800-linux directory to launch the emulator, and then added that script to Steam so I could launch it in game mode as well. E.g.;
#!/bin/bash
./a7800 a7800 -now -cart Download.a78
Mind you, a Linux-compatible frontend and, some user configuration to change the console controls to map to controller buttons instead of keyboard keys would make the experience better, but games load and play just fine on the Steam Deck from what I have seen so far.