Kobo works fantastic.
If you have the ability, set up calibre and calibre-web and you can configure your Kobo to use your ebook library as the “store”.
Kobo also has at least one plugin/mod that replaces the whole reading UI with one with more features. Check out KOReader for that.
Apart from that, though, it makes little difference what ebook you get. If it allows you to load your own ebook files on manually (afaik they all do), you can do whatever you want.
This could be as innocent as “hiring manager was on vacation and we still have some interviews planned” or “our interviewer was caught fornicating with a chicken and we’ve had to make some internal changes”.
I would take it as a positive sign that you’re still in the running, but like others have said, I wouldn’t pause my other job searching tasks to wait for this one to play out.