This GA travel card has a minimum contract period of 6 month initially. The equivalent for one month would the 1-month GA Travel Card; it has no minimum contract period and no auto-renewal. Yes, you could purchase it as foreigner as well, it is issued as paper ticket in this case.
1-month GA Travel Card | SBB
However, did you know that there is the Swiss Travel Pass or the Swiss Half Card destined for tourists?
See: Swiss Travel System