I've
just upgraded my Likebook Mars Reader to Android 8.1
Regarding the issue of this post: the stock reader does recognize and use side loaded fonts and does display bold, italic and such using only the regular ttf font file, but styles are displayed in a rather (how to put it) not so differentiated way compared with the regular style. Also, there is some problem using sideloaded freedict dictionaries.
Because of the above, I installed a side loaded v2020.03.2 of KoReader. I'm using it as my default reader software, and I enjoy the different styles of a font that the KoReader does show as very different from each other.
If and when I get any news on the subject, like an update for the device that changes the stock reader font's styles display, I'll post it here... but I'm quite sure that it won't be soon.
Kind regards,
[INCANUS]