Any competent, professional bodyshop will be able to help. Have you approached any? What have they said. Modern cars have lots of plastic panels (with lots of different types of plastic), front and rear bumper panels have been plastic for decades. A professional bodyshop is repairing and painting these panels every day of the week. Plastic repair using nitrogen plastic welders is now commonplace.
And as was explained in your previous thread on this, panels are available new, so that's probably the best way forward.