Donations for a startup? Are you serious? You should be offering equity if you are going to profit from this.
Occasionally, fanatical TV viewers will try to get together and pledge enough money to produce another season of their favorite cancelled TV show. In return for that money, they get to see another season of their favorite cancelled TV show (well, they would if the networks were smart enough to work that way).
So if I donated $5 to this startup and got a life membership with like 3 fighting dudes, while they charge $1/mo post-launch with the same plan, I'd call that a pretty fair bargain. Of course, I don't quite know the legality of selling a chance to possibly in the future own a product that isn't developed yet and might not ever exist, but at a discounted rate.