Why not use https://www.freedos.org? Or boot FreeDOS straight from QEMU. Using Debian seems incredibly bloated when the goal is to use DOS. Alpine Linux would be a better base. Then you can use real DOS or a compatible one like FreeDOS.
The Raspberry Pi isn't x86 (or even x86_64) so it isn't compatible -- you have to do (at least) CPU emulation to get a DOS-compatible hardware environment. You probably also want to do other hardware emulation for sound, graphics, etc. to be compatible with DOS software.
