A thousand thank yous to the hackers, tinkerers and documentors out there that got me my legally purchased ebook onto my legally owned ebook reader, despite all the noxious DRM.  Heartening community effort.  Equal number of eff yous to the ruinous system responsible for Adobe Digital Editions.
Quick test of desktop calendars for XFCE. Maya from elementary os didn’t sync properly with caldav (and didn’t show recurring tasks). Orage doesn’t seem to have anything other than it’s tiny view. Evolution seems like best to go with for now. Working pretty smoothly with caldav. A bit slow to open windows (e.g. new calendar appointments), and very ‘GNOME’ styled, but it’ll do.
I like that Kobo e-readers are pretty hackable. I’ve added night mode and Wallabag integration to mine, and didn’t have to do anything too extreme in order to do so. No rooting etc – just copying a few files into the right locations.