Is there any way for my app's users to be able to submit a blog post to prismic via my app?
Hey, welcome to the Community forum!
This would require a write API and unfortunately this is not a built in feature in Prismic. We've broadly talked about this in the past, Renaud gave a very thorough response about this, please take a look at his response, here:
If you have any feedback or comments that you want to share with us don't hesitate to also post them here.
Let me know if I can help you with anything else