Headless Obsidian Sync?

I’m trying to figure out how to better integrate the rest of my digital life with Obsidian, in that I want to get more information directly into Obsidian, and enrich what’s already there. I’m aware that Obsidian itself doesn’t have a REST API and the plugins related to that are all abandoned (so far as I can find). But it’s just Markdown, right? But using Obsidian Sync I cannot get to those files, unless I’m running Obsidian (correct me if I’m wrong, but there is no 3rd party Obsidian Sync)?

Anyone have a solution for getting Obsidian Sync onto a headless Linux server? Can Obsidian be run headless? Or is my only option running it on a headed server and/or some sort of shitty double-sync option? (Note: I use iOS so options like syncthings is a no go… and iCloud Sync, well, it’s not the greatest).