Since I first played with it a few years ago, I've become a quiet fan of Focuswriter, a distraction free writing tool.
Determinedly minimalist, it's best suited to the 'get it all down and edit later' approach. No structuring of the text, no inline formatting, no links, no images, it basically has the functionality of an old school mechanical typewriter.
Limited, yes, but it gives you a way either or recording verbatim notes or clattering out a first draft. Available for Windows, Linux, or the Mac it does exactly what it says. It even runs nicely in a linux container on a modern chromebook.
Now, I was idly surfing the web a few days ago looking for an old mechanical typewriter - more as an ornament than a functional device - and my search also brought up the Freewrite Traveller, a device touted as a distraction free writing device, and pretty expensive for that.
Given that you can pick up an old Thinkpad 11e with Windows 10 installed for a tad over $100 from a refurbisher, and a $10 donation to the people who produce Focuswriter, you can basically put together a distraction free writing solution for a quarter of the price of the Freewrite device.
And, of course with Windows 10 and Microsoft OneDrive you can save and backup your work to a secure location.
Of course the Thinkpad will be old and slow compared to a modern machine, but if you are using it as a minimal writing device to take anywhere, its compute power or lack of it isn't an issue - Focuswriter does not really need much in the way of compute resources.
What personally I find important is that these old Thinkpads have keyboards that are quite nice to type on and the screens are pretty reasonable, And because education authorities bought scads of them, replacement chargers and batteries are pretty cheap and easy to find - something to bear in mind when buying an old machine.
Coupled with Notable, and perhaps a markdown editor such as Ghostwriter, you also have the basics for a basic machine for research and documentation - the only real gap is the lack of a decent basic lightweight spreadsheet application to help tabulate artefacts, but Google sheets will do most of the work for you assuming a network connection, which is pretty much a universal these days.
And of course, the other thing about these machines is that they are cheap enough to be disposable. It really doesn't matter is you drop it or leave it on the bus.
I know I'm a bit odd in having multiple machines, instead of just one that you take everywhere, but I find it works for me - having an old machine that is equipped to do the task lets me focus on the task itself. What I wouldn't do is use such and old an underpowered machine (by today's standards) as general purpose machine.