So interestingly, Bookshop.org appears to have added a landing page for an e-reader:
https://bookshop.org/shop/123
GoodeReader seems to think that's indication that they will soon launch their
own, but that seems a bit premature. Given that Bookshop said, "
We are working with Kobo to support Kobo devices later this year.", I'm wondering if it the landing page will become a vendor-branded/partnership Kobo device instead.