Calc Star Wars: Visions, The Twins - Hypothetical firepower of the Gemini Star Destroyer

B-20N shows Am a simulation of the Gemini-class Star Destroyer blowing up a planet (possibly even a star system), which draws its energy from the kyber-crystal at its core, which is also the power of the Twin's dark side suits. Not only is it confirmed that the Gemini Star Destroyer can destroy a planet, but it's more powerful than the Death Star (and that it's being powered by the Twins).

The Twin Star Destroyer, “The Twins”

When you first see the Twin Star Destroyer, it emerges from the shadows like the beginning of a new cinematic Star Wars adventure. But there’s something quite different about the shape of this craft. “The Twin Star Destroyer is such a playful idea,” says Rimes. “With a wink and nod, director Hiroyuki Imaishi slowly reveals a Star Destroyer coming out of shadow. But wait — the light expands revealing a second conjoined Destroyer!”

A clever visual riff on the twin siblings at the core of this short, the expansive design fits perfectly into the heightened and sprawling world in the tale.

To mirror the occupants, each Star Destroyer contains its own throne room, one for Am and one for Karre. And in the middle: a weapon capable of mass destruction. “Holding them together is a massive cannon,” says Rimes. “When powered by the twins, it can deliver planet-eradicating blasts that would put the Death Star to shame.”

Click to expand...

So I think that justifies looking at the simulation for reference. The diameter of the Earth is 12742km.
251 pixels = 12742km
1 pixels = 12742km/251 = 50.7649402km
Timeframe is 3 seconds and 10 frames.

T = 1s/24
= 41.6666667ms X 10
= 0.416666667s + 3s
= 3.41666667s

50.7649402km X 318 = 16143.251km

T = 16143.251km/3.41666667s
= 4724853.95m/s

The mass of the Earth is 6.0e24kg.

KE = (0.5)mv^2
= (0.5) X 6.0e24 X 4724853.95^2
= 6.69727345e37 joules
= 16.006867710325226 ninatons

Final Results
Hypothetical firepower of the Gemini-class Star Destroyer = 16.007 ninatons

Given Karre and Am are a power source for it, their power can also be figured out from that. Unfortunately though, we don't know how long it takes to charge, or the connection between the twins and the kyber-crystal as of yet.