Erm. The old RDS-10 Pioner have a throw weight of about 1.5-1.75 tons.
So we could safely assume that Oreshnik have a throw weight of about the same scale - 1.5-2 tons at least.
At stated Mach 11 velocity, i.e. 3,7 km/s, the impact would be about 5-6 times more poweful than detonation of Mk-84 bomb.
Assuming that you could get plane in range.
See these posts:
Assuming 1500–2000 kg of throw weight, that leaves 750–1000 kg for warheads (PBV/shroud/fuel/guidance/thrusters/structure always takes around 50% of throw weight).
The user I linked to assumed 1150 kg of payload (ie warheads), which is actually extremely optimistic.
Their calculation assumed a subset of that mass was used for ablative coatings, nosecones, MIRV subassembly parts, etc. I'll recalculate with a single unitary warhead instead to give an upper bound estimate if they didn't use submunitions and had zero mass loss from ablation (impossible).
With 1150 kg of payload impacting at 2.95 km/s:
KE = 1/2 M V^2 = 0.5*1150*((2.95*1000)^2) = 5 GJ
5 GJ = 1.2 tons of yield in TNT equivalent
So in the impossible maximum end case, you get..33% more yield than a single 2000 lb bomb. Not very impressive.
Now you'll argue that it's actually 3.7 km/s. To that I have one thing to say – show me the proof that this is a realistic reentry speed. My ballistic missile trajectory simulation program says that this is bollocks. Historical information on ICBM RV velocities near impact says that this is extreme bollocks.
But I'll entertain your argument just for fun, even if I strongly disagree with the premise. Let's use the same totally unrealistic assumptions wrt the mass of the impactor as before.
With 1150 kg of payload impacting at 3.7 km/s:
KE = 1/2 M V^2 = 0.5*1150*((3.7*1000)^2) = 7.9 GJ
7.9 GJ = 1.9 tons of yield in TNT equivalent
So in this even more absurdly impossible maximum end case, you get...the yield of two 2000 lb bombs. Wow, that's so much bang for your buck, amazing! Totally worth burning >$30 million dollars worth of ballistic missile for! /s
Let's examine the alternative. Two Mk84 bombs with JDAM kits would cost about $100,000 ($20k for the bombs, $80k for the JDAM kits). A F-35 costs $42k per flight hour. Even if you need extensive support, total mission costs are highly unlikely to exceed $1 million (and realistically would probably be a fraction of that). You can place those bombs with 30 meter accuracy (vs >200 meter accuracy), even in GPS denied environments. The Oreshnik is functionally useless at dishing out useful levels of damage to targets due to its hideously poor accuracy. The JDAMed Mk84s are not.
The only possible reason to use a Oreshnik with conventional munitions is as a terror/political weapon. It's not a practical or cost-effective conventional weapon, but rather a thinly veiled threat: look at me, I have IRBMs, the next one could be nuclear tipped!