One night is possible - I don’t think any of the brokers have a ‘minimum nights’ requirement.
Generally how it works is people put in requests to the broker. On the other end, owners let the broker they’re interested in renting out their own points and the broker gives them access to see all the requests. Then the owner picks some requests and tries to match current availability to make the reservation(s).
So it depends on what owners are looking at the time of your request, like which points they own and which reservations match up to the amount of points they’re looking to sell.
For a single night your chances aren’t bad. Maybe an owner has a small amount of points they’re looking to use, or maybe they still have points left after doing a larger rental.