EInkBro is terrific. I filed a bug last year, the dev fixed it in less than a week. I use the stock launcher, but on an old Nook I used ReLaunchX, it was fine. On that device I only had two applications that I used anyway.
I have not tried KOReader, but I can test it for you. What features do you use?
I'll second EinkBro as an awesome browser. I absolutely cannot stand anything else on my e-book reader: Onyx BOOX Max Lumi, Firefox/Android, Onyx's NeoBrowser (rebranded Chromium), and DDG Privacy Browser installed, I only use those if EinkBro blows up for some reason, which it very rarely does.
I've had a lot of interactions with the developer and the GitHub repo, and he's been quite responsive. Hasn't addressed everything, but several features added and bugs get smashed fast.
- Termux, of course. Linux-on-Android userland. There's a suite of related apps which I also install (e.g., Termux:API and Termux:Styling.) There's a black-on-white theme which works quite well (default is white-on-black, not so much).
- F-Droid. FOSS archive repo, independent of Google Play.
- Aurora Store. Alternative interface to Google Play.
- APK Mirror. Direct access to app installs, though not managed (no updates).
- Hacker's Keyboard. Far preferable to Android or Onyx defaults.
- A podcast app. I'm using AntennaPod (FOSS), have also used PodcastRepublic in the past.
- RSS Feed reader, though I'm finding I don't make much use of this. Feeder seems to be the default.
- Internet Radio player. Transistor is one option. Not something used frequently, but handy to have.
A few others though most are very occasionally used and/or disappointments (e.g., Mozilla's Pocket App, which has been an absolute shitshow, despite potentially filling a critical niche). For the most part I avoid anything that has an account associated with it, largely to avoid distractions. Though also because tablets are shitty generative tools. Adding a Bluetooth keyboard helps slightly, but Android still throws in far too many limitations.
Oh, it was just out of curiosity, as an eInk device with a more accessible platform (compared to my old Kobo with it's old Linux system) is something I love to daydream of. Thank you for your reviews!
As for KOReader, I mostly use the epub reading capabilities, and the FTP client for getting files onto it. I've tried it as an app on my Android phone but it felt a bit cumbersome in a smaller screen, and I think the faster refresh rate of LCD panels doesn't suit it well. I do really love it on my Kobo, though.
I have not tried KOReader, but I can test it for you. What features do you use?