It's not standard, but that's not a surprise, as Markdown is a pretty barebones format. Most of what they extended it with is pretty simple, like [[wikilinks]]. There are also other tools being developed that can work with the custom syntaxt extensions.
Also, at the end of the day, it's still just plain text. You won't lose any of your data if you no longer use Obsidian.
Also, at the end of the day, it's still just plain text. You won't lose any of your data if you no longer use Obsidian.