Thank you very much for your answers, I am definitely not enough used to Github! I did a copy of my SD card before starting all my tests. Until now, no need to be worried !
@elinkser Drivers are my big problem because I write in French. Until now It was fun to deal with Koreader but at the end, I have a lot of work correcting the missing caps. It isn’t always worth it !
The best solution I have seen until now seems to be
Inkbox but first it is nearly mandatory to have linux in your tools to deals with ans second, after e few test, it is missing a bit of maturity, I encountered lot of bugs.