Essentially the method outlined by myself and Lucky Guy is the same except that I use a regular oven while he prefers a toaster oven and 25 degrees lower.
But both yield crispy skins. As long as you end in a screaming hot oven, the microwave start makes a negligible difference. It’s the dry air of the hot oven which produces the crispy skins and fluffy interior and the micro beginning saves about 45 minutes or so.
I was less specific on the time in the micro because that’s determined solely by the size of the potato and strength of the micro so you just have to use your best guesstimate and that’s pretty much the only tricky part.
And, like you, I hate store bought potato salad cuz they invariably have severely undercooked pieces amidst the rest. Nothing worse (except for the egg whites with the texture of rubber because they boiled them way too hard).
As usual, if you want something done right, you have to do it yourself :)