I am trying to convert Map[String, AttributeValue] to Scala objects. AttributeValue represents data in DynamoDB. FromAttributeValue in the below stub is used to convert basic cases

Following is code stub:

trait FromMap[L] {
  def apply(m: Map[String, AttributeValue]): Option[L]
}

object FromMap extends LowerPriorityFromMapInstances {

  implicit val hnilFromMap: FromMap[HNil] = (m: Map[String, AttributeValue]) => Some(HNil)

  implicit def hconsFromMap0[K <: Symbol, V, T <: HList](implicit
      witness: => Witness.Aux[K],
      fromAttributeValue: => Lazy[FromAttributeValue[V]],
      fromMapT: => FromMap[T],
  ): FromMap[FieldType[K, V] :: T] = ???

  implicit def cnilFromMap: FromMap[CNil] = ???

  implicit def coproductFromMap[K <: Symbol, H, T <: Coproduct](implicit 
      wit: => Witness.Aux[K],
      fromMapH: => Lazy[FromMap[H]],
      fromMapT: => FromMap[T]
  ): FromMap[FieldType[K, H] :+: T] = ???
}

trait LowerPriorityFromMapInstances {
  implicit def optFromMap[K <: Symbol, V, R <: HList, T <: HList](implicit
      witness: => Witness.Aux[K],
      gen: => LabelledGeneric.Aux[V, R],
      fromMapH: => Lazy[FromMap[R]],
      fromMapT: => FromMap[T]
  ): FromMap[FieldType[K, Option[V]] :: T] = ???

  implicit def listFromMap[K <: Symbol, V, R <: HList, T <: HList](implicit
      witness: => Witness.Aux[K],
      gen: => LabelledGeneric.Aux[V, R],
      fromMapH: => Lazy[FromMap[R]],
      fromMapT: => FromMap[T]
  ): FromMap[FieldType[K, List[V]] :: T] = ???

//Other instances as required


  implicit def hConsFromMap1[K <: Symbol, V, R <: HList, T <: HList](implicit
      wit: => Witness.Aux[K],
      gen: => LabelledGeneric.Aux[V, R],
      fromMapH: => Lazy[FromMap[R]],
      fromMapT: => FromMap[T]
  ): FromMap[FieldType[K, V] :: T] = ???
 
}

Compiler is able to find derivations for all cases except for sealed traits. How can I make this work?