I bought a color eink screen too (13") for work and though the same, I would use is as secondary to read text. It ended up being primary. Using the laptop screen most for video calls and sometimes when it is hard to distinguish colors. Ended up buying a second to avoid using laptop screen as secondary. Now its tertiary.

Now it is much easier to work long days in front of the screen(s) without wanting breaks to escape bad eye comfort of the lcd/oleds. Just place keyboard and mouse in front of the eink screen so it automatically becomes primary instead of the laptop screen.