While you can update the status of a given Loop in Dotloop, it is important to note that the status of the related Sisu Transaction is driven by the Dotloop Contract Dates, and not by the actual status of the Loop:
A Loop with a Pre-Listing status that has a Contract Agreement Date that is in the future will integrate into Sisu as Pipeline, while a Loop with a Pre-Listing status that has a Contract Agreement Date that is in the past will integrate into Sisu as Signed.
When you add a Listing Date to a Loop, this will integrate into Sisu as a Live Listing, as this reflects the listing going live on the MLS.
Please see these articles on Sisu Closed Date Handling.