What about a new section for Crostini/Chromebook?
Even a 2023 Chromebook is supported till 2031.
With the Crostini Linux enabled (a click) it has a slim version of Debian 12 in a container.
Amazingly for Google, Crostini is out of Beta.
It's neither an Android Tablet, nor a straight Linux laptop. The cheaper ChromeBooks are like the old Netbooks (no touch), but work better.
As little as £160 (discounted) for Intel models, which are cheaper because not as good as ARM.
Intel models can easily run WINE32 & WINE64 on Crostini. Some Windows VB6 using OCX and other 32bit Windows programs don't run on 64bit Vista, 7, 8, 10 or 11.
Linux
Calibre from Kovid's site works with regular install, once missing libraries are added from the built in Distro (best to
sudo apt install synaptic first to avoid guessing on the apt names, even though Wayland is used.
Firefox ESR & Chromium.
Libre Office, The GIMP, Audacity, Audacious, Grsync, KATE, Caja, Pluma, Okular etc.
MTP Android Phones and Tablets work better in Crostini Linux with Calibre than on regular native Linux.
Android & Playstore
Much works via Playstore. Sometimes a ChromeOS version. Some native ARM may not be available on Intel Chromebook and vice versa. Pocketbook, Vivaldi browser, Viber and others. Direct apk install supported.
Chrome OS
Chrome Browser: Extensions to backup firmware, add Compose Key etc work
Obviously the Google apps that are ChromeOS and work both offline and on "Cloud": Docs, Sheet, Canvas etc, but for offline Linux programs are better. It gets updates.
A single slim 11.5" laptop style Intel Samsung Chromebook gives about 6 hours (not 11 claimed) and multiple Android apps, ChromeOS, Linux and a few Windows programs all at same time with copy/paste.
I'd recommend a Getting Started "sticky" but the Android aspect is no harder than any Android and more flexible. The Linux is a bit weird to get initial stuff setup and then not much harder (more Console needed).
What else can you write in LO Writer, make an ebook in Calibre (not tried Sigil), load it into an Android app on the same screen and test? Then easier copy to to MTP phone.
USB Mass storage ereaders need to be mounted in Google FileManager and then Shared to Linux, then accessed as a folder/directory on disk. A Sony NetMD USB does work direct to Chromium on Linux using
https://web.minidisc.wiki/ It's using the built in Chromium USB driver.
Network shares can be mounted with Google's File manger for ChromeOS and Android, but the Crostini Linux can mount and remember them directly. I've not tested the Calibre Content server, but the ChromeOS settings have Linux port forwarding. There is also ChromeOS multiple monitor support (like Linux/Windows) and even the cheap Chromebooks can do HDMI via USB-C port (and charge on it at the same time in some cases) with a dumb adaptor or a USB-C monitor. Multiple desktops too.