rough93:
I do have solder experience, are you talking about using the bus system with this technique?
Yes, SPI bus. And with smart bus devices you can do without select pins through a bit of home-rolled protocol.
You would send messages prefaced by which device(s) should act on them, I'd use a simple ID number that each finger or joint would have a single bit identify it. That way you could give any set of ID's the same command (next part of the message) at the same time.
I have kicked an idea of a serial bus around where each chip's RX connects to the next chip's TX with last RX to first TX making a ring but I haven't worked that down to details. It would be slow to very slow compared to SPI but could be faster than human senses.
I'm also more practical/cost conscious about these things. Whatever the device costs to make, by the time it retails it will need to be worth at least 4x that. A lot of good ideas die commercially right there. But what you're doing is study, not end design, right? So you don't mind writing code for that and different for an end product?
PS - serial speeds.
Default SPI on a 16MHz Arduino xfers 512K bytes per second. Even 1/4 of that is 10x 115200 baud.
115200 baud serial xfers 11520 bytes per second.
The SPI messages should move quick and have more time not transmitting than the TTL serial.