With some help from Dzenik, I managed to get a working LCD on Marlin 2.x, though some of it is hacked together. Initialization isn't working the way I'd expect, so I'm manually calling the LCD init code.

After that, the LCD writes just work, though I don't currently have pixel tripling working.

Now, Mickey had already gotten the LCD working on his Marlin build - his is based off of Marlin4ST, mine is from 2.x, but we're both working toward the same goal.  I'll get the scaling working soon, then hammer out the issues with LCD init so it works with U8G the way we'd expect.