Does ECC RAM with a Coffee Lake CPU need specific motherboard support?

Question

I'm preparing to build a new computer, and I'd like to use ECC RAM if possible. In the past, that required a motherboard with ECC support, but these days it's unclear whether that's still true.

The Wikipedia page "List of Intel Chipsets" has a column for Parity/ECC support in all the tables up to a certain point. But the section "5/6/7/8/9 Series Chipsets" explains that newer chipsets don't have a memory controller because it's part of the processor instead, and the tables from that point onward don't mention ECC at all. Furthermore, Intel's ARK specifications page for modern chipsets, such as the H370, don't mention ECC, while the ARK pages for CPUs, like the i3-9100, have a line for "ECC Memory Supported", yes or no.

This leads me to believe that ECC support for modern Intel CPUs does not depend on the motherboard: as long as you have a CPU whose memory controller supports ECC (such as the i3-9100), and a motherboard whose chipset is compatible with the CPU (such as an H370 to go with the 9th-gen i3), ECC RAM should work.

But the specifications page for the Gigabyte H370M DS3H, an H370-based motherboard, says "Support for ECC Un-buffered DIMM 1Rx8/2Rx8 memory modules (operate in non-ECC mode)". The "operate in non-ECC mode" is what concerns me; that defeats the purpose of buying ECC RAM in the first place.

Will ECC really not work on this board? If so, what is it about the motherboard that prevents it from working if the RAM and the CPU's memory controller both support it? Is there a good way to find boards which do support ECC with 9th-generation Intel CPUs? ECC doesn't seem to be available as a filter criterion on shopping sites.