Tablets are Tablets

with user provided reading apps
OTOH A Kindle is a dedicated reading device with known features
There are 4 Kindle drivers to compensate for these
features
For a Tablet, the burden is on you to place files in the needed location.
Just because you use a Kindle App on the tablet... It is still a Tablet to Calibre
Connect to Folder is one way
If the driver is not used for other, similar(Android) devices. you can code an RELATIVE path in the templat
eg
Code:
user\books\{title}-{authors}