This is actually supported by both the client and the server.
To use it in mobile clients you need to specify two domain names like that: fake-sni.com|domain.com where “fake-sni.com” is the domain thay will be in the SNI and “domain.com” is the domain in your TLS certificate (used to check the server’s authenticity)
I tried the method you suggested on the Android client, but it doesn't seem to work. After setting the domain name to two domains connected by `|`, the client fails to connect to the server and remains stuck in a “connecting” state.
To use it in mobile clients you need to specify two domain names like that: fake-sni.com|domain.com where “fake-sni.com” is the domain thay will be in the SNI and “domain.com” is the domain in your TLS certificate (used to check the server’s authenticity)