Hi Max, the development goes very slow due to developer free time. Growduino OrPi version changed a few times and we had to start from scratch, but now it looks good. We have switched to http://www.orangepi.org/orangepiplus2e/ , which has wi-fi and also - and this is most important - onboard eMMC flash memory. This memory is much more reliable than microSD cards, and has also much faster read/write.
About dosing pumps - this development has not started yet, Growduino V2 has a priority.