At least they appear to be partnering with Kobo "later this year" [1]. I've been a big fan of Kobo's devices so this is a nice plus. (I just wish they could figure out some way to get Kindle exclusives, but well that's a contradiction in terms, so...)
[1]: https://bookshop.org/info/ebooks ("Can I read my ebooks on my Kindle, Kobo, Nook, etc.?")