I just wanted to say that Assimil, the publisher of the Japanese course I’ve been recommending all this time, Japanese with Ease, finally has released a digital version of the English edition. Here’s a link:
There’s still no sign of a physical copy of this edition, but there are apps that run on Android, iOS, Windows and macOS, and there’s a free trial that offers access to the first seven (of 98) lessons, so I’d say this is a good opportunity to try out this course and get hold of it if one finds that it’s suitable.
(I’m not sure where to put this because it’s not an online textbook, but it’s also not a physical textbook. I would call it a ‘digital/digitised textbook’, but it seems strange to create a new category just for one course.)