Here's my 2c. From what i have read, there is a risk of damaging your strings, or ukulele. If you are cool with that, do it! I have an old Makala Uke that is now my travel uke and would have no problem using a pick on it. My home Uke I would have more of a problem with.
If you still would like to use a pick, i have seen many videos of people using leather, or felt picks, and they sound great to me.
On a somewhat side note, I have a friend that plays guitar with picks she makes from gift cards. she likes using them because they have more give. kind of cool if you ask me lol