Its a shame WebOS doesn't support steam link still. I don't think I can wait any more longer for LG to add it to the store. I've decided to sell my LG TV and get an andriod TV just so i can use the steam link app.
Actually, I believe this is on LG's part and not Steam/Valve. As far as I know, the only official from Valve appp support is for Android. I believe the version for Samsung TVs was technology licensed from Valve but the app was actually written by Samsung themselves. With this said, I suspect the only was it'll end up on WebOS is if LG licenses it from Valve and writes a WebOS version themselves.
You would be better off asking where Steam Link for webOS is on the Steam forum as they are the ones who produce the software. If they can make it for multiple platform including competitors' TVs then they should be capable of porting it to webOS.
https://steamcommunity.com/app/353380/discussions/0/1692669912400498996/