I'll also note that different PETG materials vary a lot. I've used eSun, Hatchbox, Ovation, 3DXTech, MG Chemical, and Sunlu. The Ovation and 3DXTech have very little stringing. The Ovation surface finish is inconsistent - varies with speed, so at corners and transitions it's shiny and on long walls it's more satin. All the others except 3DXtech are shiny black. The 3DXTech is more of a satin black, and a but grayish - not a deep black.
eSun strings quite a bit, Hatchbox less - but trying to buy it these days in the challenge.