I've been using a Supernote Manta for the past month and I love it. It's not a full-on computer, and it has its own UI that discourages you from treating it like one, but it is in fact an Android device. I've installed Syncthing and a few other small niceties, and it is amazing to be able to carry a big collection of PDFs around with me that I've curated on my laptop, desktop, phone. One of the "native" apps is Amazon Kindle, which is great, because I occasionally want to read one of those books on a bigger screen. The pen is good, and feels fine, although I prefer the feel of the ReMarkable.

Downside: there is no backlight. Others claim that the screen updates are too slow to make typing practical, but I personally don't think that. I installed termux and I think it's fine. Screen updates are no worse than SSH over a cellphone connection. I have not really found a good RSS reader for it yet, though...