How can human finger pressure be measured?
There is a component called a &quot;force-sensitive resistor&quot; that I'd suggest you try. You can get them in a small, round configuration like this one from Adafruit force-sensitive resistor.

They are easy to read as they just appear as a variable resistance; as the finger pressure is increased, the resistance decreases. Make a voltage divider with the FSR as one leg, then most any microcontroller with an analog input can measure the pressure.
You can also make these yourself using a sandwich of piezoresistive sheet between two layers of conductive fabric, but the ready-made FSR is easier.
A capacitive sensor may also work, but detecting variation in pressure in a consistent way is trickier. The capacitance will increase with finger pressure, but the capacitance will also be affected by the skin's hydration, surface moisture, etc.