First of all, not everyone is good at plastering, and not everyone is equipped to do plaster. Do you really need all this for a single hole? It's a big expense for a single nail hole, isn't it?
Then you can use this trick while waiting to do major work.
Simply apply some toothpaste on your fingertips, then apply it on the hole. Then use a plastic card to remove excess toothpaste and let dry.
Toothpaste is invisible! Unless your walls are yellowed or colored! Because you guessed it, this tip is good on the white walls!
1) Remove the nail
2) Blow through the hole to remove the plaster dust
3) Apply white toothpaste on your fingertip
4) Plug the hole
5) Use a plastic card to remove excess toothpaste
6) Let dry! No one will see the modification with toothpaste! Can you find it here !?