Hi Bennsky, they are definitely not breath attacks. The purpose of the Pu-Lip-Ku-KMT-Tu is to become aware of the feeling of the RELEASE of air using unfamiliar techniques to create a greater awareness of the system.
With a breath attack there is no RELEASE as such as the note is formed around flow.
Plus, since I’m still struggling with my bottom lip curling in around a G on the staff, “Pu” attacks are near impossible for me if my lips aren’t somewhat in line. So, I find it’s a good exercise for that as well.