TL;DR
terminal
$ pip install oracledb
test.py
import oracledb
oracledb.init_oracle_client() # <- これが重要!!!
con = oracledb.connect('%connect_string%')
cur = con.cursor()
cur.execute('SELECT * FROM dba_users')
for row in cur:
print(row[0])
cur.close()
con.lose()
cf. 3.1. Enabling python-oracledb Thick mode
// 本文は後でかきます