Unfortunately, I assume that this product has been canceled a few months ago, when Intel sold their NUC business to ASUS.
There are a few small computers that support ECC and which use obsolete Intel Tiger Lake or Tremont-core-based Intel Elkhart Lake CPUs, but those CPUs are a dead end, being slow and supporting instruction sets that are different from the current mainline Intel CPUs, so I would not recommend any of them.
The best remaining choice depends on which is more important, the size and the power consumption or the price of the server.
For very small size and low power consumption I am not aware of any good solution at a reasonable price, because even when some of the Arm CPU SoCs or Intel or AMD mobile CPUs support ECC, I have not seen any such computer board that includes the ECC support. There are some industrial computers with ECC, but those are expensive for what they offer.
If only the cost is the problem, and second-hand servers are avoided because the server to be bought is intended to be used for many years, then a server with desktop Intel or AMD CPUs must be used. The MBs with the Intel W480 chipset are expensive, so the cheapest solution is to use one of the AM5 MBs that specify ECC memory support, e.g. from ASUS or ASRock Rack, together with one of the cheaper Ryzen 7000.