There is a lot of overlap between this and "modern" nixie tube clocks such as this one:

https://www.amazon.com/LONYIABBI-Electronic-Simulation-Power...

I'd speculate those came first (kinda popular with streamers and such, I think) and they basically just added a usb port. In the product video you can even see that they arrive as individual sticks to be plugged in.

It is probably easier and cheaper to have 6x separate display & microcontroller and update each one independently