They at least used to support ECC on some models of i3 chips as well.
My understanding was that was specifically to support ECC on lower power NAS systems.
Random examples:
• https://ark.intel.com/content/www/us/en/ark/products/90729/i... (6th gen i3)
• https://ark.intel.com/content/www/us/en/ark/products/97455/i... (7th gen i3)
• https://ark.intel.com/content/www/us/en/ark/products/129944/... (8th gen i3)
• https://ark.intel.com/content/www/us/en/ark/products/190886/... (9th gen i3)
• https://ark.intel.com/content/www/us/en/ark/products/203899/... (10th gen i3)
Looking over random i3 pages from 11th gen onwards though, I'm not even seeing ECC mentioned on the pages at all.
It's not a "yes/no" item like on the older generation ones pages, it's completely absent (from the ones I just checked). :(