Sounds like you won’t get better performance than the following:
Select text → Copy → Tap Shortcut
In the Shortcut, then, you’ll want to do something like:
Get Clipboard → Set Variable to “Input” → Run an action that sends the text to wherever you want it to go in order to get it into Obsidian (e.g., Drafts’s Run Action with Text).
If you need a sketch in Shortcuts to get started I’m happy to make one.