Here is how I managed to export PDFs with hand-written annotations from the NeoReader app of my Boox Tab Ultra.

  1. Tap in the center of the screen. This opens up this menu.
  2. Click on the More icon.

  3. Click on Embed data. This embeds the annotations into the PDF.

  4. Export the PDF either by clicking on More > Share or via Boox drop.

This worked for version 38136-6a1ec45f42f (38136) of the NeoReader app.