Need to buy a Video Card) Has no onboard Graphics . . . Not sure if it is worth buying a video card for system #1 and run pfsense or freenas on it.
If you don't think you'd be using the graphics very often, how about a 2D USB-HDMI graphics adapter? See here
They're only about $50, so it would be a lot cheaper than a discrete 3D PCIe graphics card. You could either keep the USB-HDMI adapter permanently attached to the computer, or you could just store it in your toolbox for when you need.
If ECC Ram is required for ZFS would buying a used server make more sense?
I'd also consider a cheap system with a Ryzen non-APU. (Cheap relative to a Xeon server.) The non-APU Ryzens support ECC as long as the motherboard does too. For example, most ASRock AM4 motherboards support ECC with the non-APU Ryzens. The Gigabyte X470 Aorus Gaming 7 Wifi also supports ECC, so I use the Gigabyte motherboard with a Ryzen 7 2700X and Kingston DDR4 2666 MHz ECC.