Sometimes the most interesting things show up on the FCC website vie Netronix.
I just found a 9.7" E-ink sign product from a company called Team Sable. Most of Sable's roducts have to do with point of sale and retail systems, and now they are getting into digital signage.
Their new sign is based around a 9.7" Spectra E-ink screen. I can't tell if it has a touchscreen, but the manual says it has a screen resolution of 1200 x 825 and is capable of displaying black, white, and red.
Powered by a 3Ah battery, this sign is compatible with Wifi, Bluetooth, Zigbee, and NFC. It's charging port is micro-USB, and there's no HDMI or other video port, which means it can't be used as a wired display.
I describe this as their "new" sign because Team Sable has been exhibiting digital signage products since at least 2017, when they showed off this sign at a trade show: