I’m just going to use this space to pass along solutions to problem that I have discovered (and I use the word “discovery” loosely…I don’t mean I discovered them, per se…rather, I researched them online and found the solution).
Issue #1 – I can’t use a custom sound for Notifications on my Pixel XL under Android 8.
Solution – I always use custom ringtones and notifications. To use a custom ringtone on a Pixel, you simply find the Ringtones folder on the device’s internal storage, and drop your MP3 in there. It will appear in your Sound Settings under Phone Ringtone as an option. However, you can’t get a custom notification tone that way. To solve that problem, inside the DCIM folder in the device’s internal storage, create a folder labeled Media, and *inside that folder*, create another folder called Notifications. Drop your MP3 into that folder (personally, I’ve used the first 6 seconds of Dobie Gray’s “Drift Away” for his for the past decade), and it will show up on the Sound Settings page under Advanced > Default notification sound. Bada-bing, bada boom! 😉