This is an Interesting ask.
Let me connect with App Reviews team to discuss on this and get back to you.
Yes, you can submit the app that's written in TypeScript.
Just make sure you have src/ - For .ts Code and app/ - transpiled code
Does this also imply I should package it into a zip file manually, to make sure the src/ directory is included? Are there resources I should be sure to include?
In case someone else runs into this, the standard fdk pack works fine: just make sure the directories are in the right place.