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. (You can find lots of enthusiasts discussing the pros and cons of Dana’s vs. Neos and offering mods if you google around a bit.)
Writers love the distraction-free environment, and I also find it great for first drafts.
Even though it’s old technology, I kinda expect it to have a longer shelf life than most things because it doesn’t require software on the machine it’s connecting to—it just quickly “types” what you’ve written directly into whatever window you have open: composing an email in gmail, writing a doc in Microsoft Word, etc.
(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. It’s basically a digital notebook that will transform your handwriting to text when you’re ready to send it elsewhere. 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.
Another thought: it might be worth trying a bluetooth keyboard with your phone on a Tiny cell phone stand —if you aren’t holding your phone, it’s probably much less tempting to click on things and get distracted — use DND! — but your typing will be stored in a very convenient place.