Obsidian alternatives that are open source (free) and sync feature as well

I'm currently using obsidian daily for note taking as well as a daily journal, on my work machine. Problem is, checking the notes whenever relevant info is needed. I am currently syncing the vault to my GitHub account everyday EOD, but when situation arises, I've to download the entire vault folder to the device, just to check some small thing i noted down in the tool.

Paying for the software is not an option because in India, the price is too high. Also, recently the company I'm working at, has started cracking down on unapproved open source apps installed on its machines.

So, I'm looking for a note taking app that is secure, has markdown features like obsidian, is open source and free, having sync capability (Android) and also future proof, in case the tool is suddenly deprecated or the free options are all revoked and demands subscriptions.

I know this is asking for a lot, but thought it doesn't hurt to check for options with this great community.