Is Neauvia organic filler effective and how long does it last?

Fillers alone will improve your acne scars very little. I wouldn't expect PRP to improve them at all. A combination of treatments will be the best way to approach acne scars.
A Fraxel laser would usually be the best first step for acne treatment. This will tighten the skin as well as make some of the depressions more shallow.
Other depressions can be treated with fillers and subcison (elevating the depression by dividing the underlying scar with a needle) may be necessary for this. Generally, the benefit from a filler alone is limited, but it can be helpful in certain patients. You need to make an appointment to see a PS with experience in this field for a definitive plan of action.
I would not worry about organic fillers. the most important aspect of a filler is how long it lasts and its viscosity. Hyaluronic acid fillers are natural to the body anyway, and an organic filler may not be.
Thank you for your question, and best of luck to you.

Reissa. I am not familiar with that filler. You have raised a couple of areas that are concerning to you that should be addressed with a systematic approach of options to address each. Acne and scars can be tricky and I would have to see a photo to make recommendations; however, I cannot see how filler of any type would help. Scar indentations usually do not respond to filler injections underneath to "pop" them up because the skin is usually tethered down to the deeper tissue by tough bands of scar tissue. There are a whole list of ways to treat acne and scarring from that. My advice is to see a dermatologist or cosmetic surgeon with experience in this area who has many different tools and techniques to improve your look; and, has results that display that skill.
Best, DrG