What's the self hosted ecosystem like for these? Let's say I have my own ebooks and audiobooks. Is there whisper sync like features?
Some of the Kobo also support audio books. All of them have microUSB or USB-C to sync, some got Wi-Fi or Bluetooth as well. Mine even has a mic for some reason.
There's a plethora of hacks for devices like the Kobo (reMarkable is another one). For example, see [4]
Self hosted in Docker, I browse to the book I want, add it to a ‘shelf’ that is synchronised. then on the Kobo I press sync. It downloads.
I used a guide that was something like this:
https://jccpalmer.com/posts/setting-up-kobo-sync-with-calibr...