I support this as well.
I was surprised to discover that the “Share” option works for PDFs, and actually saved the annotations to the file in my Obsidian vault rather than saving a new copy. (At least for me – Shaiya, did you test this?)
However this is not at all obvious.
And it’s not fully functional: “Share” also let me open an image file, but I got an error when I tried to edit it (“Couldn’t load file”).
Related feature requests
For the record, there have been at least two other feature requests for this, with no resolution, but they closed due to inactivity.
- “Open in default app” on Mobile
- Open PDFs and images in external app on android tablet
- And a request for a setting to always open PDF files in default app, which I also support: One-click PDF files opening in default system app