Great project ! Feel free to check out the exxp repo if you ever want some insights on how we did things: https://github.com/drov0/exxp
I also wrote at length about how we managed two-way integration and let users comment on hive with wordpress accounts: https://peakd.com/steempress/@howo/how-we-let-non-hive-users-interact-with-the-hive-blockchain-with-steempress-a-case-study
This was 5 years ago so there might be a better solution now but food for thought
Some quick advice from the top of my head:
You need to setup cannonical links otherwise people who already have a blog will see their SEO drop. It's as simple as adding it in the json_metadata, see this post as an example: https://peakd.com/arduino/@howo/buildingatimetrackerusingarduinoandblockchaintangletimepart2-mok7qjklgy
{
"json_metadata": {
"canonical_url": "https://brokencode.io/building-a-time-tracker-using-arduino-and-blockchain-tangletime-part-2/",
....
}
Keychain integration is great and a good innovation on avoiding the "manage the private keys" issue + no need for a server, although this prevents people from scheduling posts and I know bloggers tend to do most of their posts scheduled so this might be a blocker in the future, maybe there's a way to trigger a notification on the mobile app ? I haven't coded with keychain in a while, cc @stoodkev.