I'm not sure if PB has to support Grammarly or vice-versa, but creating this feature request if PB has the power to do so.
I use Grammarly's browser extension and it adds this intuitive option to correct all the language mistakes in my content:
It works with almost all the text fields on almost all the sites I open. PeerBoard doesn't support it. It would be great to see PB utilizing the power of Grammarly.