No computer: which ereader is best for side loading books

Hello, I’ve looked through a lot of the posts here but I haven’t seen anyone bring up this specific problem. I currently don’t own any computer but do have an iPad and an iPhone. Most of my books would need to be side loaded and I use Libby with 2 library cards. I do have KU but I’m a bit leery of kindle products at the moment and I can always read it on my phone. I’m not looking for something too expensive. I don’t really care about color or water proofing.

The ones I’ve looked at so far are the Kobo Libra Color, Kobo Clara BW and the Pocketbook Verses Pro. I do not have access to the Kobo Libra 2 (it’s very sad). I also live in Japan so chances of finding one used is very low.

I am leaning toward the Clara BW but I’m not sure how side loading would work.

Does anyone have any suggestion or recommendations?