Meh, it seems very one off with no further elaboration. Here is my rough calc being generous. It takes place in Invincible #67 and without looking deeper it does seem to be something quickly mentioned and then forgotten.
Star = 50 pixels = 1,391,000 km
Solar Disk = 82 pixels = 2,281,240 km
Radius = 1,140,620 km
We don't know the thickness, I will assume a low, mid, and high end of 1000 kilometers, 10,000 kilometers, and 100,000 kilometers
(pi(1,140,620 km)^2 * 1000 km) = 4.087256e15 km^3
(pi(1,140,620 km)^2 * 10,000 km) = 4.087256e16 km^3
(pi(1,140,620 km)^2 * 100,000 km) = 4.087256e17 km^3
This is a disk, not a planet, so I can't use GBE. I will assume 'totally destroyed' means atomized. I will assume it's made of Carbon Fiber, which means atomization equals 156,545 joules/cubic centimeter
- Low End: (pi(1,140,620 km)^2 * 1000 km) = 4.087256e15 km^3 * 156,545 joules/cubic centimeter = 6.398395e35 joules
- Mid End: (pi(1,140,620 km)^2 * 10,000 km) = 4.087256e16 km^3 * 156,545 joules/cubic centimeter = 6.398395e36 joules
- High End: (pi(1,140,620 km)^2 * 100,000 km) = 4.087256e17 km^3 * 156,545 joules/cubic centimeter = 6.398395e37 joules
And, being generous, let's assume Nolan is 100x higher than this and then round up:
- Low End: 6.398395e35 joules * 100 = 6.398395e37 joules --> 1e38 joules
- Mid End: 6.398395e36 joules * 100 = 6.398395e38 joules --> 1e39 joules
- High End: 6.398395e37 joules * 100 = 6.398395e39 joules --> 1e40 joules
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For comparison, VSB has Bardock scale to King Vegeta who is between 6.000245e37 and 7.553202e39 joules. At best, Nolan might be more powerful than SSJ Bardock here if you use the low end for Bardock and use the high end for Omniman scaling here, but I am being very generous. The reality is the low end for Bardock's scaling here would be a hair's weaker than the high end of what Omniman scales to here, and that's in base.
Also quite frankly I grossly exaggerated the calc assuming the atomization of carbon.