Recommendations for upgrade to color, larger size

I've been usibg a Kobo Clara HD for several years now and am interested in getting an upgrade - preferably an ereader that is much larger and can handle color. I have a few rextbook pdfs and epubs that really do not work on my Clara - they are too large for the screen and don't resize easily, if at all. Math equations in particular get mangled, and reading a CSS textbook on a b&w device gets a bit silly.

I don't care about online storage features, syncing, etc, though a connection to Libby/Overdrive/etc would be nice to have. Not critical, as my libraries don't have much on e-offer that's on my reading list, and I don't yet intend to completely ditch my Clara, but it would be nice. I do not use an ereader for audiobooks.

I found the reMarkable Paper Pro, which seems to be one of the few products serving my needs - it seems quite hard to find ereaders that are both large and support color, to say nothing of bells & whistles I don't need. Saw at least one reviewer offering up the Onyx Boox Note Air 3 C as an alternative.

What would y'all recommend? The assistance is much appreciated.