I am a Linux enthusiast and probable expert, and using it since 1993 on the command line (today with zsh) (and Unix since 1987, SunOS3.2).
I personally have a Huawei tablet, details here. With an SD card.
I also have a Logitech Bluetooth keyboard case for that tablet.
I need to be able to read some PDF documents on the tablet without a working internet connection. (at my work at CEA/LIST - a quite bureaucratic organization since indirectly related to French nuclear warheads, I have a powerful Dell workstation with
root access & Ethernet connection to the Internet under Debian/Unstable - so sometimes Xorg does not work properly -, but no access to the corporate Wifi; for the clips-rule-gcc project I prefer to read the CLIPS documentation on my BYOD tablet).
If my tablet was good genuine Linux Debian system, I would just
wget http://clipsrules.sourceforge.net/documentation/v640/bpg.pdf when Internet is available, and later
evince bpg.pdf when it is not, taking advantage of
zsh auto completion facilities.
What are the equivalent on Android 8 ?
My AppStore is google, and I was not yet able to root my tablet. Dreaming of that every day.