The Onyx Boox Max 2 Pro is a powerful (if expensive) eReader tablet with a huge 13.3-inch hi-res E-Ink display. The reader boasts a quad-core processor, a full version of Android 6.0, and a highly responsive E-Ink display, but there are a few drawbacks.
https://www.notebookcheck.net/The-Onyx-Boox-Max-2-Pro-is-a-quad-core-E-Ink-tablet-coming-for-800.269604.0.html
"Coming this month"
"Android 6.0"
Those two things together should be a red alert to anyone involved in this project that they've gone off the rails. Android 8.1 just came out. There is absolutely no excuse to be releasing a device now with anything less than 8.0. Not even having 7.0 means they clearly don't care at all.
$800!?
Buy 2-4 Samsung tab A tablets which come with wacom pen. Sync all of them, just swap them when one need charging. High contrast for outdoor? Get a matte screen protector. Nobody is fond reading while getting baked in the sun, they'll go indoor as fast as possible. If the weather is good to bathe in, then you most likely can read without high contrast stuff.
Another company is gonna bleed money because they are crazy.