This is the first time I’ve even heard of CoreELEC despite using LibreELEC. Thanks for mentioning it. I have doubts every obscure cheap Android box is supported though.
LibreElec reduced official support for SBCs with Amlogic Cpus (like the Odroid C2, Odroid C4, and Odroid N2) in 2018, that spawned the fork called CoreElec. Then LibreElec removed Amlogic support entirely in 2019 (they wanted to just focus on Raspberry Pi SBCs). That caused a mass exodus of users and most moved to CoreElec. That was around the same time cheap TV boxes started appearing on AliExpress, and a lot of them happened to have Amlogc CPUs like the s905X, s905X2, s905X3, and s922X, these are the same CPUs in Odroid C2 and Odroid C4 and Odroid N2, so CoreElec was able to add support for most of them.
CoreElec remains tied to LibreElec upstream, receiving the same updates.
They have a comprehensive, accurate and up-to-date hardware compatibility list. They don’t support all Chinese TV boxes, but if it has an Amlogic CPU, there’s a high chance it is supported. If you’re unsure, just look at any one of the hundreds of “will this cheap TV box work?” threads on their forum.
The average consumer doesn’t buy android TV boxes from AliExpress. They use a Google Chromecast or a NVidia shield, or Amazon Fire TV.
The people who buy these devices from China are those deliberately looking for specific hardware to use for a specific application.