I know Robot Manager is a great tool to monitor RPA / RDA robots. In our project there is no work flow involved and Robot implementation only is required. There is no case type, and there is no need to install Pega Platform environment. In such Robotics only project, if customer wants to see all the Robot status (active or inactive) is there any OOTB tool or simple approach to build such functionality? Installing entire Pega Platform and Robot Manager only for this is, I feel, too costly (a set of hardware, maintenance costs, version dependencies, etc).
Robot Manager is the out-of-the-box solution for this functionality. Any other solution to this is one you'd need to provide and build/maintain separately. Other than the hardware, you might check with your Practice or Engagement Leader to see if there are any licensing costs associated.
A typical small setup might include only a single Windows Server to run both the platform and the package server (in addition to a database server you may already have capacity in-place for).