But compare the length of the lists for e.g. Samsung and LG with those for Huawei or Xiaomi. You're much less likely to find a ROM for a random Chinese device than for the large brand phones that are somewhat common in the US. It might be because Chinese manufacturers are even less concerned about the GPL (I once tried to look for kernel sources for my Huawei device and only found dead links) or maybe Chinese developers are less involved in the LineageOS community, but it's more likely than not that there won't be any LineageOS build available.
You can normally buy the complete source code together with CAD models for all the plastic parts, circuit board designs and datasheets for all the chips for $50 on those super dodgy chinese source code exchange websites.
The only problem then is typically getting it all to compile will be many person-months of work. There will typically be hundreds of toolchains, many missing, lots of build scripts missing or wrong, etc.
