Can non-HD Android devices output full HD over HDMI? What is the chance Android 4+ phone or tablet with physical HDMI-out connector will be able to output FullHD resolution if the device itself does not have FullHD screen? Are there any rules for this? What if the device's screen resolution is even smaller than 720p (like 800x480)?
There aren't any rules for this, so it's entirely up to the tablet in each particular case. I can give an example: the original Asus Eee Pad Transformer TF101 has a &lt; 720p screen, and its HDMI output is a pixel-for-pixel mirror of the screen (i.e. the HDMI output is the same pixel size as the screen).