We are evaluating the possibility of changing SOM. We currently use VIA processor with imx.6 with many problems in the operating system because they are not upgraded.
Kiosk mode (hide the boot)
small linux and Qt
OpenGL ES 2.0
USB for pendrive and tochscreen
¿Olimex has source code operating system and good supports?
Your best bet is to look at the product pages.
If you must have LVDS that may be a serious limit on what works for you.
In case you don't know, google can be told to search only pages for a site e.g.