I wonder how it would look to connect the columns with 0201 zero-ohm resistors between the LEDs (jumping over the rows lines). If you want a square pixel pitch it might work out nicely.
You don't really have the clearance for that. The gap between the two pads of the resistor should be at most 0.3mm, and more realistically 0.2mm - any larger and they're going to tombstone. 0.1mm traces with 0.1mm clearance are manufacturable so it could fit in a 0.3mm gap, but realistically you probably want to do 0.15mm traces & clearance to keep the cost acceptable.
