Lifting Strength Recalculations[]
First off before getting into the new feats the current LS stuff has to be downgraded, unfortunately, as they're based off pushing boulders but don't account for friction, instead scaling the entire weight to the characters. Hard rock on soft rock is 0.65 so that should do.
Tanjiro Boulder: 17199 x 0.65 = 11179.35 kg/11.18 tons
Gyomei Boulder: 81621 x 0.65 = 53053.65/53.05 tons
Both in the same class as before.
Swamp Demon Punch[]
Feat here. Average hand volume is roughly 375.6 cm^3, which I will increase by 15% to account for the various cracks it made. Wall seems made of rock (Vfrag value = 69 j/cm^3).
431.94 cc x 69 j/cc = 29803.86 J, Wall level, less than twice baseline, yikes.
Father Spider Punch[]
You ever think about the fact that this guy could have been called Daddy Longlegs? What a waste man. Anyway.
Feat here, but there's a bit of an issue, it's being done underwater (in a pretty shallow river) so it's hard to tell where the crater ends, so I've calculated it including an end for the radius where I think the crater ends from what I can see and one for where the panel ends (there's a lot of rocks fling around but it's unclear if they're being knocked upwards or just away from the point of the punch.
Can't find any way to get crater height so as a lowball, the 8 px thing is the diameter of one of the bigger stones.
I'll use Father Spider's fist height for pixel scaling. Ratio between my fist's width and height is 0.847x. Average hand width is 8.89 cm (which teaches me i have really small hands it seems) x 0.847 = 7.529 cm, average height is 175 cm, 320 : 175 = 145 = 1.828 x 7.529 = 13.763 cm. Bit rough but I hope it works.
By the way, the result is almost identical (slightly lower but perspective makes this method better IMO) if you use Tanjiro's head as I did before scribbling it out so it's mostly consistent.
Height: 13.76 : 13 x 8 = 8.47 cm
Low End: 13.76 : 13 x 145.14 = 153.62 cm -> Volume (spherical cap) 33761.28 cm^3 x 8 (frag of rock) = 270090.24 J/0.0000645 Tons of TNT, 9-B
High End: 13.76 : 13 x 265.24 = 280.74 cm -> 62637.05 cm^3 x 8 = 501096.4 J/0.0001197 Tons of TNT, 9-B