I’m not convinced this would make a worthwhile addition to Obsidian directly.
I use pens extensively for hand writing and drawing; all my devices have been chosen because they have sophisticated pens. So it’s nothing to do with that.
All the programs that come to mind with this ability have databases and export. Google Keep, Samsung Notes, OneNote, Evernote plus all the specialised programs. I think it’s the same with Apple. Markdown itself doesn’t have image capabilities, though it can link to image files. Remembering where you are in the drawing and supporting multiple undos is much easier in a database, and I’m not sure how practical it would be with files, especially between sessions.
The programs that support handwriting usually have OCR. Keyboards on many devices have the ability to transcribe into text. This already exists and is constantly developed within these other programs.
I find it quite simple to import the handwritten or drawn files into Obsidian using attachment folders and this works quite straightforwardly. I’m very unconvinced that a separate Obsidian feature would significantly enhance this workflow, but I’m sure it would absorb a lot of development effort.