That looked interesting as a self-hostable project until it got to the requirement for a $3200 AMD board. Maybe the price will come down one day...
Perhaps with a single camera you could port this to fit on a Zynq 7000 footprint with something like a Pynq Z1 or Numato Styx, which are in the $250 hobbies price point for example.
The Zynq Z7030+ chip would probably be able to get the job done but aren't as common - https://www.lcsc.com/product-detail/Programmable-Logic-Devic.... The Kintex 410T-480T are available new <$160 from reputable vendors, used <$50 from less-reputable vendors - they do have the performance (and overall IO) for this task.
Regarding the Hailo featured in the article, a few of us have been messing with it on a Raspberry Pi 5[2], and it offers more performance in a similar power envelope. The major downside is availability. I can buy the Coral on many electronics supplier sites, but Hailo seems to be selling through 'Product inquiry' right now, which is not easy to navigate as an individual!
[2] https://pipci.jeffgeerling.com/cards_m2/hailo-8-ai-module.ht...
BTW, is it possible to have 10 of these connected to a single board/cpu ?
https://www.lcsc.com/product-detail/Programmable-Logic-Devic...
(420T/480T are priced similarly new.)
Didn't have enough time to dive into it yet and still working on some other project, but this still tickles the back of my head and would be cool even if I could only run mnist on it.
To use it with an FPGA accelerator you also have to build all the "hardware" to run said openCL kernel efficiently, manage data transfer, talk to the host, etc for the FPGA. This is very foreign if you're only used to doing software design and still very nontrivial even if you've done FPGA work, though I think there are some open hardware projects around doing this.