Brief update.
The hardware I have is actually a Mac Mini 2012. I think I had 2014 on the brain when I originally reported the model number, because that's the oldest model that actually will run the latest macOS, as of this writing.
I had forgotten about a bunch of SSD's I had sitting around unused. I got them back when SSD for PC was relatively new and expensive, and not expected to be as reliable as mechanical HDD. They are small, 128GB. The original plan was to use 4 of them in a RAID 10. One drive did fail (good thing it was a RAID). The speed gain from RAID wasn't huge, so for the rebuild, I decided to just use a single larger SSD for the system hard drive, and keep the actual data files on a mechnical disk. So, just used one of the leftover SSD drives reformatted for attempted Mac Mini upgrade.
Tried using Time Machine to perform a system backup prior to hardware upgrade. Never used it before, but had another Mac Mini on the LAN, so used it for the storage device.
Replacing the old HDD wasn't especially difficult. Found a YT video to guide. The parts aren't machined that well, though, so the unit didn't want to go back together just right. After trying for a couple hours, just patched it back together with chewing gum and bailing wire, and called it good.
The attempt to restore from Time Machine was an epic fail. There were no problems at all booting into recovery mode and having the new SSD recognized. But the recovery software couldn't recognize the backup file on the second Mac Mini (which is only about six-months olds, so has M1 processor and latest macOS). Resorted to reinstall of macOS from internet, which for that units was Mavericks. Was able to install and boot to desktop. Installed some updates to Mavericks. Then tried to update to Mojave, but I wasn't allowed to select it. Tried Catalina, same deal. Then El Capitain was selectable, but hung during attempted installation and couldn't recover. Tried everything I could think of, perform disk partition, erase disk, but nothing would get rid of the corrupted installation file. It kept trying to install, but couldn't.
Briefly looked into installing Ubuntu, which I think is a great option, and something I'd like to try, but realized that would require some additional learning, and may require more time, So I decided to try and load Daphile.
What a smooth and easy install that was. I think it may have helped to already be familiar with LMS and Squeezelite, but really, everything just worked. Used Balena Etcher on Win 10 PC to create an install USB stick, and I was off. What a relief!
I think once Raspberry Pi's are available again, I'll get one to use as a player with piCorePlayer, and try loading Ubuntu on to this old Mac Mini, but for now I can use this easily.
Thanks again everybody.