Using Callouts in Obsidian and GitHub Flavored Markdown
GitHub now officially supports callouts (they call them Alerts and they are the same syntax as documentation on Microsoft Learn)! The real nice thing is that they match the syntax that Obsidian decided to use for their callouts.
One thing to be aware of is that GitHub has 5 distinct styles that aren't distinct in Obsidian where there is use of aliases for some of the callout types. For instance:
> ![warning]
and ![caution]
In Obsidian produce the same callout styling:

In GitHub they are distinct:

I've been taking advantage of this new support to write support documentation for work in Obsidian and copying and pasting over to my GitHub files which has been very convenient.