dafang still_image works fine if you use the template from their github. I had to add the username, password, authentication type, and verify_ssl=false
- platform: generic
name: Camera
still_image_url: https://192.168.x.y/cgi-bin/currentpic.cgi
stream_source: rtsp://192.168.x.y:8554/unicast
verify_ssl: false
username: root
password: ********
authentication: basic