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.
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
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.
<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.