What are the typical roles and responsibilities of a Technical Program Manager at Amazon? Are they focused more on engineering design work or are they involved with coordinating between different teams to deliver products like a typical Technical Delivery Manager?
They are involved with coordinating between different teams to deliver products.
Is it concerning if your potential future manager has lots of years of being a technical program manager under his/her belt especially if you are joining as an SDE? Because I imagine they would be better as people managers rather than engineering managers
Engineering managers are "usually" better people managers since TPM doesn't have any reportees. YMMV.