in hooktheory II secondary chords are explained to great detail when working in a major scale and their quality is always major and dominant 7 and always introducing one note that's outside the scale. however there's very little said about the quality of secondary chords in the minor scale, for example a V/v (major secondary chord) in the minor scale introduces 2 scale degrees that are outside the minor scale in one chord making it extreme dissonant but if you convert that secondary chord to a v/v (minor secondary chord) then only one note outside the scale is introduced making the chord a lot easier to work with and accommodate.
so, are secondary chords in the minor scale minor?
Secondary dominants are always major because dominant resolution is defined in terms of V in the major key. The same chord in the relative major, V/iii, also introduces 2 scale degrees outside the major scale.
The secondary (major) supertonic (ii/) is minor, but Hookpad does not have this yet.