Currently it's very limited, but the BeTrusted Precursor is in the ballpark:

https://www.crowdsupply.com/sutajio-kosagi/precursor

I wrote a little about it today, as it happens:

https://www.theregister.com/2025/09/12/three_new_microkernel...

I just got back from a trip with the Mudita Kompakt - not quite what you're describing, but close:

* 4.3" monochrome e-Ink display

* no web browser, no email client

* de-Googled Android; only way to load apps is via APK from a computer

* hardware switch to turn off all radios, for the privacy-concerned

The built-in software is still a work-in-progress (eg the music player hasn't got FOLDER support yet!) but you can find e-Ink-friendly apps on repos like F-Droid.

Remarkable devices runs standard Linux under the hood.

I ran into this thing someone built and is releasing kits for. It won't be near as smooth as PalmOS, but if you're into hacking a little bit, it might be worth looking at.

https://www.youtube.com/watch?v=VPQ2q7yVjZs

I've seen some other people hack together similarly devices. One was a Raspberry Pi 0 with a blackberry keyboard and a screen.

Anything off the shelf and even remotely polished these days is likely running Android, which seems like it would defeat the purpose.

The are Remarkable Move might be an option, if you're looking more for a notebook to organize everything, but if you want a Palm-like experience, that will also miss the mark.

You could try for an old Palm or Handspring device off eBay. It might be its own island, or getting in syncing could be a project.

You can run old Palm ROMS on smartphones. I tried it, but once the nostalgia wore off in 5 minutes I gave up on it. It also seems to defeat the purpose of what you're going for.

Boox Palma, or Minmal Phone, maybe?

This reviewer reviews e-ink devices: https://www.youtube.com/@ChalidRaqami

Best dumb phones 2025: https://www.youtube.com/watch?v=FwkLjrNMd3M

I have a ReMarkable tablet and it's pretty nice. It's large, yes, but you can get a keyboard and then it's a word processor and Linux terminal. Use emacs or ssh into a bigger machine. Plus it's just regular linux and you get root shell out of the box.

There are smaller devices in a similar vein, I hear good things about Kobo.

E-ink tablets are about the best thing I can think of here. Second best option is probably just an old Android device without a sim card.

"At the time", running on the device was a requirement.

"Nowadays", one-the-device is harder but don't we always get enough connectivity to run web-based apps? Or at least apps through a browser? Whatever device, but our own apps from our own servers? New advantage that there is not much residing on the device which can then be lost, stolen or broken without issue.

I’ve never used a palm pilot, but I do have a Furi FLX1. If you don’t run the android container in it, then you aren’t exposed to the duopoly.

It works as a phone. It works for documents, contacts, calendars etc. Bluetooth keyboard and mouse work, as does a USBC dock (but no DP).

I like it a lot.

Superbook has some neat eink devices.

Remarkable just came out with a small eink tablet that could kind of work.

PostmarketOS might run on some existing devices as well.

Used palm pilots are likely too if productivity apps are mostly what you're after.

Not exactly what you want, but I recently discovered my old Palm Pilot IIIe still works when I put batteries in it.

Portable music players might fill this niche if there was an OS which could support the hardware.

device that runs open source software

To a first approximation nothing like that exists and while I understand philosophical commitment, from a getting shit done perspective, it is an unnecessary requirement.

For better or worse, that ship sailed long ago because it has no commercial viability.

Yes, it might make an interesting hobby project, but running any old phone might too.