I've tried playing with PkgConfigBR and Requires but didn't manage to make it work smoothly - simply because quazip doesn't have pkg-config file. And I guess that might be the reason for such behaviour (i.e. all the details could not be resolved without pc file hence it's up to devel to place it properly). So ended up installing it manually as well into the sandbox.
I've tried to install some apps and most of them didn't work. Here is the full list : - Stopwatch - works - Timer - doesn't work - Timer+ - doesn't work - Steps - doesn't work - Misfit - doesn't work - Cards - works but can't load data - Love Weather (watchface) - doesn't work I can't find why the timers don't work, they are simple apps :s.
And this lead me to this question : is it currently possible to remove an app on the PT with only a Jolla phone ?
qdbus org.rockwork /org/rockwork/B0_B4_48_80_B9_87 org.rockwork.Pebble.RemoveApp 1e420b43-63be-45f7-822c-2a7d57a55384
I also noticed than after extracting apps to the right folders, they are available on the PT only after restarting rockpoold.