RA8875 or SSD1963

Hello all,

so I'm still looking for a reliable tft touch screen display for my project, I have tried a few displays from ebay/alliexpress and have been a bit disappointed with either their performance or reliability, I think I need to spend a bit more to get the desired results. If I'm going to spend a bit more then I might as well go up in size, so far all the ones I have tried have been less than 4 inch. I've singled out a couple candidates

1: RA8875 5inch 800x400 spi or parallel (buydisplay(eastrising))
2: SSD1963 5 inch 800x400

I like the idea of the SSD1963 but am a bit put off by the price and that it appears that there are less problems if you use a due rather than a mega, which then means I have to use 3.3v logic when I have a 5v encoder to read and power plus a stepper motor driverDM556() that I think requires 5v signals.
As I understand it both these have flash memory to store fonts/glyphs, the SSD1963 can be flashed while the chip is still on board, with the right software, and the RA8875 has to be flashed then soldered to the board. I would rather use the RA8875 purely because of the cost.

So I suppose what I want to know is how do you add fonts to the Flash chip on the RA8875?