While the MVP was to validate the general idea and making sure the pieces fit together, the milestone friends was all about bringing digester to a state where I could tell a friend "hey, check this out". Specifically, this included Facebook login and blog subscriptions.
Supporting these new features and bringing digester to this state was tricky, because I was imagining how a user might add a blog's url. Would they directly enter a link to an RSS feed or would I have to find the feed myself? Obviously, I can't anticipate what they are going to do, so I had to implement both and then test with a ton of blogs to make sure I handle all the different formats and follow links correctly. This works now for most cases with some (hopefully-) negligible exceptions.
On the login side, integrating Facebook was more difficult than Github, which was the only one so far, because I first had to create a Facebook account. When did so, they immediately flagged my account as "under review" and to this date, I haven't heard back from them. I then created a second account using my old phone number and they accepted that.
I am now going to tell some people about digester and hope that they sign up. After that, I want to further improve the product based on the feedback and eventually post it to some wider audiences like hackernews or producthunt.