I mean they have the PRO class Ryzen processors that do officially support ECC ram. You can't really buy them new unless they're in a prebuilt server or used on eBay. I wish they were easier to obtain because that new Ryzen 9 Pro 3900 is pretty awesome.It would be great if AMD had an ECC-capable enthusiast-class processor, BUT I want it paired with a true workstation class motherboard. I am completely put off by every single Threadripper and Ryzen motherboard with the black PCB's, RGB lighting, whizzy fans and plastic plates with stickers and other wiz bang stupid features, and the ridiculous names, geeez! How about they ditch all the fancy crapola, paint, and stickers, and focus on making a quality rock-solid board.
The ASUS Pro X570-Ace is basically the only workstation AM4 board. It does have an IPMI-ish system built in but I've heard nothing but horrible things about it. What we're really missing is Supermicro doing something or anything with the AM4 socket.