Still doesn't seem to sideload directly?
and are you still getting the "Could not find a top-level .pdx file" error message? if so, please make sure are uploading the deep_deck_ff03.pdx.zip file and that it truly is a .zip file :)
i know i might be writing something really obvious here, but i just know, that the "Could not find a top-level .pdx file" message shows up, when you try to upload a .zip file, that does not contain a playdate game. but this .zip file really should :D