Puppy is running as a "full" installation on the RP, like the other distros. That is what we call PUPMODE=2. There is no initrd and no aufs/unionfs layers.
Installing the 'devx" for compiling C/C++/Vala/Genie/BaCon is easy, see instructions for the "full" install situation on this page:
...probably we will do something to make this even easier in the future. Maybe just an icon on the desktop. If anyone has any thoughts on a nice way to implement this, you are welcome to contribute.
Regarding the bootup time I reported 59 seconds, that was actually for alpha1. I have just now measured for the upcoming alpha3, and ...wait for it... bootup from power-on until desktop fully loaded and ready to go is just 24 seconds!
You don't expect that kind of bootup speed even on a desktop PC, and on the RP it is incredible!
Also, everything starts so fast and is very responsive, for example the biggest app, the Chromium browser takes about 6-7 seconds the very first start, after that, on subsequent bootups the first start is about 4 seconds, and restarts in the same session about 3 seconds.