My iPad Pro M4 has also served as an e-reader. Does a good job at it for me, others may be more demanding when it comes to e-readers. Every time I considered buying an e-reader, I would stop and think that I would then be carrying around two tablets; in the end, it just didn't make sense for me to purchase an e-reader.
I have a few Kindles. I pretty much only use the Paperwhite 4 on vacation (beach/poolside) or long haul flights nowadays.
I buy my ebooks from Kobo and the whole dance of converting and loading them into the Kindle is a chore. I do have a Kobo reader as well but I prefer the feel in-hand of the Kindle.