I'm sure the Pixel 2 Launcher is a fine piece of software. I use the BlackBerry Launcher because it's lightweight and offers the exact functionality and customization that I want. It's like the Pixel launcher minus the Now feed and persistent search bar, but it retains upward swipes on icons to launch their widgets and adds both icon size/grid and a dark theme for the app drawer. I'm sure Nova does the same but I'm already subscribed to BB apps. I also disable anything I'm not using so it's like the stock launcher isn't even there. The rest of the OS remains un-skinned and un-bloated.
Regarding your question about tweaks beyond AOSP, the Pixel and Nexus line have always had a few things that others didn't have with a truly pure AOSP build. The Pixel had Night Mode in Nougat yet the AOSP build didn't. AOD comes to mind as well since it was in some phones' Developer Mode (OP5 was one) but wasn't part of the OOB experience. I expect the Pixel 2 to be similar with small tweaks. My point wasn't about big stuff, just tweaks and random features.
It won't work. It'll break.
j/k