Are Skin Boosters Restylane Vital for wrinkly tummy area safe and effective?

I would advise against putting fillers in your tummy, as I think based on your picture- you would do exceptionally well with a few microneedling treatments. Microneedling treatments can be great for improving skin texture and the appearance of stretch marks. Filler will add volume and plump up those areas creating a potentially “smooth” appearance, but not fixing the actual problem which is skin laxity.

no risk at all except to your wallet from spending large amounts of money and seeing very little return.  gaining weight would probably smooth out the skin better than any injection, but then you've gained weight again. sometimes there is no easy treatment.