Is the cocoonababy nest with stomach band considered a safe sleeping environment from birth until baby tries to roll over?

Red Nose recommends that all babies are placed for sleep in a safe cot, on a firm, clean, well-fitting & flat (not elevated) mattress

Many products on the market today do not promote a firm or a flat surface.
There is a risk to baby of being placed to sleep in an elevated position that may facilitate baby’s neck being flexed forward to the “chin on chest” position.
Also portable sleep surfaces, like the one you describe, do not have Mandatory Australian Standards for infant sleep

When a baby falls asleep in a propped up device the head can fall forwards, pushing the chin down towards the chest.
This can lead to the airway becoming blocked and reducing airflow.
https://rednose.org.au/article/bouncinette