Sony LIV app is now officially available for LG WebOS TV 2018 model onwards i.e UK6300,SK,SM and C8,C9 etc. onwards. They haven’t specified the WebOS version as such.
Hotstar app was full of errors when it was launched last year but believe me it was miles ahead of the newly released Sony LIV app.
The app is very difficult to use even on C8 OLED, freezes and what not.