Try implementing a shared map type where access is protected by a mutex and otherwise works just like Go's builtin map type (which is a generic map type).
It's honestly hard for me to tell whether you're trolling or not, but all you need to do is compare and contrast the API of the built in map type and sync.Map. One has compile time type safety and the other one doesn't.
If you want a more motivating example, try implementing generic array operations such as reduce, scan, each, reverse etc. Ideally these should be as easy to use as this example:
x := reduce(func(a, b int)int{return a*b}, []int[1,2,3])
y := reduce(func(a, b string)string{return a+b}, []string{"a", "b", "c"})
Rob Pike implemented "ivy", an array programming language, in Go but producing something like an array programming package that can be used from Go (sort of like NumPy for Pyhton) can be very messy to use or implement (even with the use of reflect package).
bakul's point is that it's not already implemented--Go's existing map doesn't have finegrained synchronization, and you can't write a generic map that does.
Or, for another example, you can't write a generic LinkedHashMap, which is a weird data structure that allows you to write constant time LRU caches, and which I presume Go doesn't have.