I just don’t have the volume right now to get good prices from manufacturers on any bigger displays.

I’m looking into 10 inch displays right now, but they are already significantly more expensive.

At some point it just drives the price of the end product up too much.

The largest devices I'm aware of are E-ink displays. Onyx produces the Onyx BOOX Mira Pro, 25.3" diagonal, based on the E Ink Carta, 25,3", resolution of 3200x1800 dots, 145 ppi, 16 shades of grey.

<https://onyxboox.com/boox_mirapro>

Note that the pixel density is markedly lower than other e-ink devices. For smaller devices, e.g., the Poke 5, DPI is more than double at 300 dpi (comparable to a laser printer): 6", E Ink Carta Plus, 16 shades of grey, 1072 × 1448 dots, pixel density - 300 ppi

<https://onyxboox.com/boox_poke5>

Granted: with increased viewing distance, resolution can fall somewhat, but given that areal density falls as the, well, square, this is 4x lower resolution.

The Mira Pro runs an eye-watering $1,750, further impeding the viewing experience. Given price trends on other E-Ink devices, I'm pretty sure that's all but entirely driven by the display cost itself.

Unfortunately AFAICT, Onyx BOOX still isn’t publishing their Linux kernel modification or sending source on request which is a violation of GNU GPL 2.

Yes, I'm aware of that, and it's a strike against the company.