>>816
これでどうだろう

import subprocess, os
my_env = os.environ.copy()
my_env["PYTHONIOENCODING"] = "cp65001"
input_text = 'あいう釙'
line=""
p = subprocess.Popen(('C:\\Users\\aa\\AppData\\Local\\Programs\\Python\\Python310\\python.exe C:\\Users\\aa\\Desktop\\ohayo.py'),stdin = subprocess.PIPE, stdout = subprocess.PIPE, shell=True, env=my_env)
line=p.communicate(input=input_text)[0]
print line

後出し条件追加は控えてくれると助かる