God invented Shields. So that you can plug the display straight into a Uno.
I have described how to modify the shield to access A4. This gives you I2C bus.
If you are not using the microSD, you have D10-D13
I suggest that you always leave D0-D1 for Serial comms through the USB cable.
The Uno clones with SMD AVR have got A6, A7 pins.
Although these display shields use most of the pins, they are still practical for many projects.
Sometimes I put Arduino headers on matrix protoboard. You need to crank the pins by 0.05" because the D8-D13 header is not on an 0.1" grid.
Recently, I just buy a green Protoshield pcb which already has the correct footprint for the Arduino headers. Then mount a STM32 or ESP32 module on the matrix. This is easier than cranking the pins of a stackable 8-pin header.
David.