I have multiple printers, an ender 5 and ender 5 plus and want to be able to run them from one machine instead of having multiple pi’s to worry about.  The mini pc is a quad core celeron with 16gb of ddr4 and 12gb in storage.  Has anyone done this before?  The machine will be domain tied but isn’t part of a wsus policy that auto updates the os.  Is this a stupid idea?

mini-pcs have grown into attractive alternatives for raspis in light server/IOT roles. They don't have the GPIO functionality at which raspis excel, and they're relative power hogs, but they are also generally more expandable and powerful for server roles than pis, which are prized mostly for their low price, and (sort of) lower power consumption.

Not sure how good it will be running octo in a docker on a SFF pc - that'll depend on your processor and memory, but it's not wrong or insane to do it if it meets your needs.

I have seen (once) multiple Ender 3's connected to a pi 3 running Octoprint.

There's a way to add GPIO to a laptop or mini pc.