For posterity sake I’m posting the final verdict in case anyone else comes looking with the same problem.
I eventually found that despite a driver package supposedly dated 2013, the most recent version of linux that actually supports the ATI Radeon HD 4570 GPU dates back to 2009 and even then people were starting to have trouble. I found numerous forum posts from 2009-2013 all reporting total failure in installing different distros with that GPU. The amazing part of this is that they were still selling brand new laptops with this GPU in 2009!
So it’ll run in 1024 mode and that’s it. Not terribly useful these days. Oh, I did notice one apparently contradictory thing … when the os asks for the user password before loading the gui, it’s in 1920 resolution, even with nomodeset, but as soon as the gui loads, it switches to 1024 res. Close, so close … but not close enough. 