I'm curious how rust academy and andysoiam servers are able to render images in their UI without graphics settings having any impact on the quality of images. I suspect they're accessing the bundle, wonder if anyone has any ideas/thoughts.

I would suggest looking at Image Library.

We've used Facepunch.Sqlite.Database which is what Image Library uses, but the rendering of images in the UI is still impacted and honestly the performance between a local HTTP server and sqlite isn't good enough to justify the complexity of storing a binary blob into a database. I'm defintley noticing every image they used is a prefab in the asset bundle server side. It would be nice to display game images/icons like they do without having to worry about the quality settings. 

If you are sending UI with Png (not URLs) then it should not be impacted.