The idea is actually not new, and KrakenD successfully uses this approach. But I'm going to bet on more developer-friendly SDKs for plugins/middlewares and a more human-readable configuration without unnecessary magic. Plus, I have no plans to commercialize the project, so any features will be available absolutely free of charge to everyone.
Synchronization would definitely be interesting. I currently use Obsidian for notes, but without a paid subscription - I just keep a folder of notes in iCloud Drive.