You're trying to create and sell a version of dos box? These companies have not replaced their computers because to the user there is no separation between the computer and the machine it controls. So the computer will be updated along with the equipment, which is not connected to the internet or a network anyways so it's not a cybersecurity risk. For the user, if it runs fine, there's no need to update just the computer, and the computer is updated along with the machine

In other words, these are embedded systems.

Not exactly, freely available solutions are already good enough for people who just want to run their apps on modern hardware, and have been for a long time. What I was thinking about writing is a tool that eases migration by using interrupt and I/O hooks to detect common patterns and, say, builds a modern SQLite database as the business uses their dBase program. Whether anyone actually needs this, I don't know.