We suspect the problem you are facing is not being able to scroll the Grid rendered inside the Dashboard Layout. We checked from our end but unfortunately were unable to reproduce your reported issue. Since the stack blitz sample, you provided is not opening, we were not able to check the scenario in which you are facing this issue.
So, we have prepared a sample for your reference. In this sample we have rendered two grids in the Dashboard Layout, and you are able to scroll the grid in this. Please find the sample below,
If your issue is still not resolved or if we have misunderstood your query please get back to us with more details like, the scenario in which this is occurring, runnable sample, code snippet used.
Please let us know if you have any concerns.