I would like to use a nano for this job, which requires 20 digital outputs, 1 analog input and transmitting via TX pin. Can D1 be TX while D0 is a digital output? I don't require RX.
After Serial.begin, do:
UCSR0B &= ~(1 << RXEN0);
to turn off RX functionality on the pin and let you use it as a normal pin. Be aware of the potential influence of characters coming down the serial line on your project.
Why do I have that code handy? I did the same thing… https://github.com/SpenceKonde/AzzyProjects/blob/master/433mhz/TowerLight841/TowerLight841.ino (line 144 - right after that, i set the pin input pullup - it’s the switch on my refrigerator door, you see, so that the tower light can blink a distracting pattern when I forget to close the refrigerator door so i’ll do so, or when there’s too much crap in front of the door for it to close right. The pile of electronics crap I’m trying to get rid of is right next to the fridge, so that’s a problem…)