Finally the Arduino library shows enough features and I have built and tested some modules. The boards have been partly assembled (everything SMD) and shipped from @Elecrow. I added the through hole shield connectors and RCA jack and programmed the character bitmaps into FLASH. Now I have opened my brandnew Tindie store and have stock for sale. Code and documentation can be found on my Github.
BTW, the manufacturing was flawless and communication with Elecrow was delightful.