That is a different issue. That's probably because of the A/B system that Pixels use. Lineage hasn't implemented that for the original Pixel either. That is not

That is a different issue. That's probably because of the A/B system that Pixels use. Lineage hasn't implemented that for the original Pixel either. That is not a limitation to modding per se. The real limitations to porting software, once you get beyond the bootloader, are always blobs, free drivers, kernel updates etc. At least with Pixels, they use treble. So you should be able to build AOSP with their provided blobs without too much trouble.