Hover state cannot be triggered by API, though you could update the data to specify a highlighted fill color for the hovered slice that would essentially look the same.
To hide the piechart itself, you can specify the pie.radius
to some very small value (zero does not work as it is ignored):
pie: {
radius: 1e-30
},
legend: {
enabled: true
},
labels: {
enabled: false
}