I found a message from JavaCardOS in this post viewtopic.php?f=28&p=2118:
And also we provide card OS customization service now. We can customize the card OS according to your own specified requirement. Believe that this service can meet your needs meanwhile with the best price.
In fact, for our project, there is no need to let the java card support all the JC API function. We only need some of them.
So, if we send you the specified java card OS requirement, can you customize java card OS for us? What about the price for this service?
Thanks