I've seen there are two distinctly different types of PMs for greenfield and existing products. Product Managers for greenfield and technical program managers

I've seen there are two distinctly different types of PMs for greenfield and existing products. Product Managers for greenfield and technical program managers for existing products. Their focus tends to be different. Product managers focus on making sure that the product solves the customer problem. Technical program managers focus on ensuring things like quality and supportability are built into the product. Sounds like this might help solve the problem at FAANG.