Start Opera with custom command line arguments and attach operadriver.

import selenium.webdriver.chrome.service as service
import subprocess

from selenium.webdriver.remote.webdriver import WebDriver

# Port 55000 is just an example, choose any suitable value here
debugging_port = 55000

subprocess.Popen(['Path_to_opera_binary', '--remote-debugging-port={}'.format(debugging_port)])
service = service.Service('Path_to_operadriver_binary')
service.start()
wd = WebDriver(service.service_url, {'operaOptions': {'debuggerAddress': "localhost:{}".format(debugging_port)}})
wd.get('Malicious_site_URL')