There are two clear ways to do this: charity or work. GoFundMe is charity, TaskRabbit/etc is work. Unless you can communicate very clearly why the middle ground of not-charity-not-work is better, I don't think you'll be able to compete with service that have a much clearer proposition.

I've read your post/comment and I don't really understand the difference between this and GoFundMe/TaskRabbit. It seems some users would use it as basically a TaskRabbit replacement, and some would over-value their time because it's sort of a donation platform. If I (and others on this thread) have read a lot of detail about the platform and don't understand the core value, I don't think someone reading a ~10 word advert will on Facebook will, and that's the format you'll need to be able to win on.

I suggest coming up with a very succinct way of pitching the service that makes it obviously better than a job or charity (both of which have many existing solutions). I wish you the best of luck with that.