Phaujairrie96
On those particular bus connections you mentioned, the postal bus does not take any significant detours from the railway track. Therefore a regular point-to-point ticket for a bus connection (e.g. B611) costs exactly the same as for a train connection in your specific scenario (the p2p ticket pricing being km-based).
In other words, in this case you’re getting exactly the same p2p ticket at the same price for both train and bus connection options if buying a regular ticket based on the online timetable.
So if the same p2p ticket is valid for both train and bus in this particular case, the same would also apply for the monthly travel card.
But this is just my educated guess, therefore please get a 2nd opinion… either here in this discussion (someone else confirming below) or at a SBB ticket counter in Visp or Brig, before venturing on a postal bus with your travel card.