PHASE 1:
Support standard line item properties that are added to products through input properties.
This covers most use cases where themes and some apps add line item properties.
PHASE 2:
Add a 'Step type' for 'Line item property' to allow fields for personalisation like 'Personalised name', 'Engraving', or 'Gift message'
This would be a Biscuits native way and would include some nicer UX to match the rest of the bundle form.
These options could be presented as:
  • Text, Textarea, Checkbox, Buttons, Dropdown values
The values would be captured as line item properties on the bundle items.