For those who dont know, the KOReader app (installable from the Likebook Appstore (different from the Play Store)) has pdf reflow in it. If a pdf file has roughly the same boring layout throughout the book/document, this is a very viable way to read it.
And even if it doesnt, this is the best way to read f.e. scientific papers on the device. The only thing that changes if there is an abrupt layout change is, that you will have different font size text segments within one page. Thats not great for reading, but it still beats all other forms of handling a pdf file thats too big for the screen.
Interestingly enough, the chinese version of boyues pdf reading app also has this option available to it, the english version has not..
How to enable pdf reflow in KOReader:
Reflow working well:
Reflow encountering complex layout on a page:
Also - funnily enough the Likebook Mars renders its pages internally in color:

Because who cares about overhead in 2018.

--
Looked around for a chinese product sheet to find out what specific options were doing, but boyue doesnt even support manuals in chinese. Quality company targeting its quality consumers I guess.
But what I found were official figures for the battery runtime:
180 hours (=7,5 days) standby, local reading for 60 hours (=2,5 days - wifi off, screen brightness set to 0), read online for 50 hours (=2 days - wifi on, screen brightness set to 0) - they dont sound exaggerated, so I guess its nice to have them. Source is boyue.com (a website so misconfigured, it sends Chrome desktop to the wep portal, but allows Chrome on a mobile device to view the desktop version, with an additional click ..

)