I cannot select messages from ST only - it’s either ‘All, Contacts Only, Favourite Contacts Only or None’.
I had it set to ‘none’ before - I now have it at ‘favourites only’ but that includes family & key friends not just ST - as I want to receive calls from the same group during DND (the options are the same for calls and texts). I cannot see an option to allow only texts from one source - ie ST, whilst allowing calls from all my favourites.
As family and friends usually text for the mundane rather than calling then during DND I do risk having more disturbances.
Android 7