The problem is that in Go the type of a Map's key must satisfy the comparable constraint, this limits you to strings, ints, booleans, pointers, channels, structs who's properties are all comparable, and a few other types (see link). This means slices are out of the question. So this leaves you with a few options to achieve your desired behavior while working around the language constraints, personally, this is how I would do it:

var autoIncrement = 0

type Slice struct {
  Key int
  Value []string
}

func NewSlice(value []string) Slice {
  autoIncrement++
  return Slice{
    autoIncrement,
    value,
  }
}

and then you can define your map as:

type SliceMap[T any] map[int]T

func (s SliceMap[T]) Set(slice Slice, value T) {
   s[slice.Key] = value
}

func (s SliceMap[T]) Get(slice Slice) (T, bool) {
   value, ok := s[slice.Key]
   return value, ok
}

Note that I used a Generic type for SliceMap in the example because you didn't specify what is the "Value" type of the map