How can you open a URI from the command line?
As shown here, you can use these commands:

am start -a com.llamalab.automate.intent.action.START_FLOW -d content://com.llamalab.automate.provider/flows/13/statements/1


or

am start -a com.llamalab.automate.intent.action.START_FLOW -d content://com.llamalab.automate.provider/flows/13/statements/1 -n com.llamalab.automate/.StartServiceReceiver


Replace content://com.llamalab.automate.provider/flows/13/statements/1 with your flow URI.

The first command worked for me while the second was giving an error in Termux and result=0 in Terminal Emulator.