AFAIK: Pressure (or lack of) won't be a problem for two reasons:
1. I believe that the hold is pressurised (otherwise pets travelling in there might get a bit uncomfortable... and I remember the cause of a crash a while ago was the hold door wasn't shut = drop in pressure in hold which 'sucked' the cabin down, rupturing to fuselage)
2. cocnuts are very strong!

As for legality:
importation of fruit, or cheese, or honey, or you-name-it = hmmmmm
better check with the country .