Greetings @flavio.f,
An expander should certainly be doable, in fact we have other customers who’ve done something similar. One example is this thread here: Enable MCP23S17 driver on TorizonCore
This customer used a MCP23S17 16-Bit I/O Expander with SPI Interface. The one thing to keep in mind is making sure a driver for whatever expander you choose is available. If it’s available in the Linux kernel you can request we enable the driver if it’s not already available, similar to what the customer in this other thread did.
I don’t have too much other details to provide than that since I personally haven’t integrated such an expander myself. But judging from other customers it does seem certainly possible.
Best Regards,
Jeremias