Using something like DOS is neither preferred nor more safe. Last time MS DOS received a security patch was 23 years ago. It's open to pretty much any security vulnerability you can think of. In case you depend on a DOS app it's preferable to run it on a modern OS that is DOS compatible, windows 10 32bit for example (I believe Win11 still has support). Or even better sandboxed in an emulator like DOSBox on a more secure OS.

I really don't want to rely on security through obscurity... MS-DOS was written back when every programmer trusted everything that ran on the computer, security wasn't even an afterthought, and encryption was the sole domain of math nerds, conspiracy theorists, and the nerd equivalent of doomsday preppers because it was "too computationally expensive." Its sole saving grace in terms of security is that it doesn't support multitasking so malware can't run in the background, but you can just target whatever software it's running, instead.