Thank you Jakob for the pointer to that FAQ entry. It’s exactly the answer I was looking for.
Therefore I have to manually convert it like this:
x := []int{1,2,3}
fmt.Println(toSliceInterface(x)...)
func toSliceInterface(p []int) []interface{} {
s := make([]interface{}, len(p))
for i, v := range p {
s[i] = v
}
return s
}