rpg-28 is best russia has , its not exported and strictly controlled , its better by 20% in penetration then any rpg-7 od -29 round... on the other hand its single use and also fragile.
I doubt that.
The 125mm RPG-28 dates back to the late 1990s, and yes it is strictly controlled in terms of exports, but it is fully operational with Russian Army units.
It is hardly fragile... it is packed in its own protective container unlike RPG-7 or RPG-29 rounds and as the rocket itself is the majority of the weight of the system compare with the light fibreglass tube launcher then carrying 2 rounds per soldier is about the best they could manage whether it was a disposable launcher or not.
It would not surprise me if they didn't come up with a new launcher hybrid with external warhead (like the RPG-7) but with a tube diameter large enough to allow a significant rocket motor to be fitted.
Of course I rather expect the RPG-32 might be adapted but with 135mm or 152mm tubes for even larger calibre rockets.
The other area of growth potential would be full calibre tandem warheads to improve penetration with lighter more powerful explosives and liners used to minimise weight.
those penetration values are also under ideal conditions and usually something is off during combat ,besides exported rounds are slightly less performing and rough conditions more or less damage the detonators making them less sensitive and late on detonation.... and the correct timing is crucial for good penetration.consider a round going 200m/s ,if the detonator is off by 1 milisecond thats 20cm od distance closer to armour and plasma beam is not forming well.
Goes both ways of course... not all armour arrays were made perfectly and during operational life standing outside in the heating of the day and freezing of the night cavities can form, rubber liners can perish and fail etc etc. A lot of the protection supposedly from angled armour comes from the angle of the plate, so a low velocity round like an RPG has a more curved trajectory and actually often impacts at a slightly nose down angle which reduces the angle of incidence of the penetration which reduces the effectiveness of angled armour.
Equally the layers and spacing of materials used are often optimised to stop a particular type of penetrator so different materials of penetrator can effect the protection level of the armour array too.
For instance having a DU layer might shatter some forms of penetrator, yet with other materials it might vapourise and become far more deadly to those around the impact point for centuries to come (unless it is cleaned up of course).
If an individual wants a man portable cheap and simple weapon to open a tank the RPG-28 is not a bad choice.