There's risk of lawsuits if you accept help like that. Best thing in your case may be to contribute to free (as in speech) software Android apps (perhaps Firefox needs more hands?).
Lawsuits from people seeking help?
Yes, open source is always an option, but there are a lot of people out there who need help on small things, specially startups. Where do they usually go?
Lawsuits _for_ people seeking help. Someone could take help and later be sued for not having compensated the creator for the work and thus not carrying the right to use such work (usually no contract is valid if it says something like "I just give this to you and get nothing in return".