

Sorry for the late reply. The optiplex is absolutely sold as a desktop, but I’ve been using it as a server for a couple of years. Very small, quiet, and it sips power, but it only has support for 2 2.5" SATA drives (though it does have plenty of USB 3 ports if you don’t mind using external storage). TrueNAS installed on it would be similar to your Synology setup (without the vendor lock in), though not nearly as convenient as the front bays you’re used to.
It’s yours if you want it, but no worries otherwise.
No worries! Yes I’m absolutely still interested, and I have the optiplex set aside for you.