They discontinued the AlphaSmarts, but they're so beloved that there's a strong market for picking up used ones. They developed a number of models (I think initially targeting usage in schools), and the newest is the Neo2.
Writers love the distraction-free environment, and I also find it great for first drafts.
(there are also new electronic typewriters that are trying to achieve the same thing — I’m sure you’ll find them if you google — but I’m turned off by how expensive and weirdly hipsterish they seem to be 🤷♀️)
Update: the ReMarkable maybe belongs in this section. A friend of mine has one and let me borrow it for a series of coworking sessions in a state park. It was a pretty good format for using at a picnic table in the woods. I’ve also heard good things about Amazon Scribe, but I’ve never tried it.