A bright child who is nursery age needs formal education like a hole in the head. It is desperately important that they learn the social skills they need for life. A well run nursery is good place to foster a range of skills.
If a gifted child is bored with nursery/ reception its often a sign of autism and if anything they need more learning through play rather than less. Possibly an autistic child might need an adult to show them how to play and foster good social skills. There may be bright children who need intensive help with their social skills who aren't autistic.
A really bright child will learn faster through self directed play than sitting in a classroom doing formal actvites.