Ok, thanks Max.
RE: SendGrid
I don't just want to send an email. I want to click on a button in my App and have it trigger a conversion of selected database content into a file (.csv, for instance) that is then appended to an email. I don't need to use SendGrid, per se, I just need the file created and then appended to an email that can be sent by the user using their on-board email client (gmail, etc).
RE: Saving a file directly to the device.
How do SQLite and IndexedDB help me achieve this? I am using Appery's database set-up.