I wouldn't do this as desktop app. That way you are fighting the existing ecosystem. Instead have a webservice that eats the RSS feed of an existing blog and mirrors it, also keeping track of uploaded images, and then when need be spins up a blog instance on digitalocean.

Wouldn't know how to price that, and with RSS often containing just a few items you'd need to think about that when setting up the blog. Though maybe blogspot supports range requests for RSS?