I use just note performer 3 with dorico. Unfortunately glissandi don’t work at all in dorico and when I want to have string harmonics sounding I neet to notate them in sounding pitch with the harmonic’s circle sign on top. Since these sounds are very high, reading of notes in sounding pitch is a quite difficult task.
In Sibelius I could get the correct harmonics sound using the common notation showing which note is being fingered and on top a diamond-shaped note (a fourth or fifth above, depending which harmonic pitch you want )
When will Dorico handle harmonics notation in professional/correct way like Sibelius?
When will we hear glissandi working?
Only the team will know when, of course. If you search the forum for harmonics you will find some discussions and workarounds… e.g. this thread 
Steinberg Forums
Chromatic/discrete-note glissando playback (i.e. not using pitch bend) will be included in the next major version of Dorico, but harmonics playback will not.
Having discrete-note gliss. in the next version is great news. I imagine the various forms of gliss: harp, violin/trombone, & keyboard/mallet instruments is a real challenge (not to mention Bartok’s use of gliss among string harmonics).
Kudos for the work you are doing.