Lineage OS is an aftermarket OS. It is released as is, without guarantee and any liability.
A comercial OS is another thing. It needs to be supported. And manufacturers of hardware parts need to support them as well to some sort. Furthermore, to publish an Android OS (with Google Mobile Services), it is a requirement that it passes the GMS Compatibility Test by Google.
(This is a sort answer. You should dive into the #epic topic regarding updates to see the full picture and all the moving parts involved in the process.)