Feedback, Feature Request, Greyscale highlights

I had the pocketbook era colour for a while, but had to replace it with the kobo libra colour as it was a better fit for my needs (highlighting, marking up text with a stylus), but I always preferred the pocketbook experience. The new inkpad one is very tempting honestly, though the lack of a colour screen is keeping my wallet in my pocket for now. Besides being able to discern the colour of an image, highlighting and marking up text in different colours is also very useful to help organise and categorise notes. With the era colour, highlights can be sorted depending on which of the 4 colours were used. With the inkpad one, there is only one colour to highlight text, so this level of organisation is absent.

This got me thinking, why isn't there greyscale highlight options for the b/w models? As I understand it, there wouldn't be a technical limitation, as different shades of grey are seen on images etc. A dark grey and a light grey would have enough contrast between each other, using hatch-style patterns would also be a way to generate enough visual contrast. Having 4 greyscale highlight styles that were mapped to one of the colour options would make sense for compatibility/interoperability. I tasked AI with a mockup, and I think it works quite well. Let me know what you think.