@DIYprojectz: It should be possible to put the encrypted root filesystem on a different device than the boot partition, though I've never tried it with an SoC or Armbian. Thanks for the idea. I promise to look into it, but don't expect immediate results as I'm busy with other things at the moment.
It depends whether you want to add expansion board someday or not. If you do, 14x14x6 heatsink is the better choice, otherwise choose 14x14xsomething according to your desire and budget. I would recommend a fan regardless, those things get hot. You can read about mounting a fan here (SBC is very similar Orange Pi R1, fan mounts the same). Here you can buy the heatsinks, check Aliexpress too maybe they are cheaper there. I also strongly suggest cutting one of the heatsinks to fit on the RAM module, it benefits too.
DIYprojectz got a reaction from gurabli in Orange Pi Zero (512MB) heatsink