From here: https://help.miro.com/hc/en-us/articles/360017572054-Sticky-notes
But it doesn’t explain the API part of your request.
Pasting from a spreadsheet
You can also copy data from any spreadsheet and paste it on the board as a cluster of stickies, where each sticky note represents a single cell.
- Copy cells from the spreadsheet using Ctrl + C (for Windows) or Cmd + C (for Mac)
- Click the canvas (you do not need to open the bulk mode)
- Use Ctrl + V (for Windows) or Cmd + V (for Mac) to paste sticky notes on the board
Each cell will be imported as a sticky note. The maximum number of cells that you can paste at a time is 5000 (but not more than 50 rows and 100 columns); the maximum number of characters is 6000.
Please note that this feature is not available in the Internet Explorer browser.