I am planning to write some integration for sending order status update to Mulesoft every time order status is updated in Salesforce, what is the best way to achieve this? (streaming API, platform events along with Process builder etc)
I would suggest the use of Platform Events. You can create a structure with the type of operation (Create/Update) and the related record Id (in case you need to query information on Mulesoft afterwards).
Then you can publish them using Process Builder with the neccessary criteria and/or Apex triggers.