Both Hermes and Pantsir use radio command guidance for the initial flight phase. The difference is that Pantsir uses radio command guidance all the way to impact with the target, while Hermes uses it to fly to the target area where its terminal guidance will find the target and get a lock and then guide itself into that target.
The website mentions that with a more powerful booster the Hermes could be used to 100km ranges... I would assume it would fly a ballistic flight path to the target area and then perform a steep diving attack on the target in such a case... a bit like a BVR missile where it is fired to the estimated target area. It would be easier for a missile for ground targets because they move less.
Remember with its warhead of nearly 30kgs it is not just for use against tanks and armoured vehicles, it can be used against all sorts of targets including radars and even enemy artillery.
It seems both Missiles, Hermes and Pantsir use radio guidance, Hermes partially, could make both missiles useable from both systems in optical mode with radio guidance.
That could make Hermes cheaper, but it would become a line of sight only weapon. The reality is that the Pantsir missile is already such a line of sight weapon so if you wanted to use the missiles that way you could use the surface to air missile instead of the ATGM.
This is good option for Pantsir, which defend S-300/400 in case if enemy ground unit succeed to come close to their positions. On the other hand Hermes could use Pantsir missiles as cheaper missile in self defense against attacking planes.
I would think the other way might be interesting... using MMW radar guided and IR guided Hermes missiles against aerial targets in a swarm aerial attack as fire and forget missiles so they could handle more targets simultaneously.
I would expect the Pantsir missile can be used against ground targets and Hermes could be used against aerial targets but each would be more effective against the targets they were designed to kill. Though a heavy target like a transport (ie AC-130U) or heavily armoured aircraft like an A-10 could warrant a 30Kg HE warhead of a Hermes to bring it down perhaps.
Of course the issue with the ground Hermes system defending itself with Pantsir missiles is the lack of ground to air sensors like search radar. It will have the equivelent of the guidance radar because that is used to send the radio commands to manoeuvre the outgoing missile towards the target (in this case the target area).
From the picture of Hermes you post, I have impression, that Hermes more looks like Grad MLRS, than ATGM like Kornet or Khrizantema. It could be positioned far behind front lines and fire missiles on enemy targets as other artillery batteries.
If you look at the mockup on the KBP website they have two trucks, one with lots of missiles looking very much like a Grad launcher, but of course larger than 122mm calibre and of course with two stage terminally guided missiles. The other truck has an extending arm with the tracking radar antenna used to track targets and guide missiles with radio commands.
The KBP website also mentions eventually using larger booster motors and one assumes lofted flight trajectories to achieve flight ranges of 100km. This would certainly mean huge potential for engaging enemy targets like artillery and even armour in rear staging areas, or enemy HQs.
Maybe will Hermes be part of artillery units and work together with artillery recce system and CPs to engage targets and be connected with them with data links. Maybe in that case Hermes could also attack tanks from the top.
It would certainly make sense to field these vehicles with artillery to take advantage of their recon assets to find targets quite deep in enemy territory. There is talk of extending the range of the 300mm Smerch rockets from 90km to 120-150km and they already use UAVs to find targets and for post attack damage assessment. Having guided missiles to hit critical point targets might mean supplementing the use of missiles like Tochka. Of course some targets need a heavier hammer than 30kgs so Tochka with its 500kg warhead will still be useful.
These missile vehicles will be able to operate further back from the front line than Shturm vehicles and even Krisantema.
I would think there will still be a need for Krisantema because it will be cheaper and able to operate with other tracked vehicles.
I could see a Ka-52 operating 50km behind enemy lines finding targets and sending launch and target information back to a Hermes unit 20km behind friendly lines and observing the result of 5 or ten missiles falling down from the sky into the thin roof armour of the enemy tanks at supersonic speeds...