@jkane figured out that the Edge Client is based on QZ Tray, a local Java web service that allows printing from browsers. If I go to the Demo page at qz.io, I see this:
Which is the browser asking for permission to connect to the local service.
It’s an open source project but has some commercial support. It sounds like Epicor may have added the capability to read/write files local to your computer based on comments here on the group.
As mentioned, it doesn’t matter if you’re on-prem or SaaS. This solves the problem of printing (and some file operations) from the browser, i.e. Kinetic UI.