Hi @LizParry ,
Yeah, we can create a flow in the target environment first so that we can create a Service Principal connection before importing the solution.
Steps:
1\ Create flow in target env
2\ Add dataverse action to create a Service Principal connection in target env
3\ Now we can find the Service Principal connection in this env.

4\ Export the solution
5\ Import the solution and it will pop up a dialog to let you choose the dataverse connection
6\ Select the Service Principal connection created before.

Now you don't need to create an unmanaged layer for this managed solution.
Hope it makes sense.
Best Regards,
Wearsky