Hi. The Web View action is not working with a local electronic device: a home cinema processor with local address https://192.168.1.140:10443/. The page loads in Safari and chrome without warnings after including its certifidate in Keychain.
I have found a workaround setting up a local reverse proxy (Nginx) to forward requests to the HTTPS server and serve them over plain HTTP. WKWebView can load http://localhost without SSL errors.