Multiple TTL sensors on serial RX GPIO 10

Use a MUX IC between the sensors and the pin. That should work.

While I have not been able to find a way to read multiple TTL sensors on a single GPIO pin, I did find this way of using other GPIO pins as serial RX pins via the pigpio library. Works great.

http://abyz.me.uk/rpi/pigpio/python.html#bb_serial_read

And a link to simple python code for reading a given GPIO pin as serial:

https://www.rs-online.com/designspark/raspberry-pi-2nd-uart-a-k-a-bit-banging-a-k-a-software-serial