I use a kingwrite EMR spen on my samsung devices, it is my favorite.
The eraser works perfectly on the back of the device but I did notice the side button does nothing.

I would imagine a regular spen user would be annoyed that it doesn't erase but I would appreciate if it could be a chosen option to have any tool you wish.

I would like to change mine to be the select tool for when i have to move things around.

BTW for Samsung Users if you need another Smart Pen I highly recommend the KingWrite pen on amazon!! The spen nibs fit perfectly on them and you get an extra fun eraser feature on the back.

End of my request, thank you for reading =)