While you can use the Pay to ZBD Gamertag endpoint to make a direct Bitcoin payment to a given ZBD user, if for whatever reason you’d want to create a general Lightning Network Charge / Payment Request QR code, you can use this endpoint.
The response payload will include a invoiceRequest which is the contents of the Charge / Payment Request QR code. Do note that Charges have defined expiration times. After a Charge expires it cannot be paid, simply create another Charge.