The Walker fired a .44 cal round ball or conical bullet and could hold up to 60 grains of black powder. As such, it was closer to the load of a .44 cal rifle of the time, and would get energies of above 1000 ft/lbs ME. ...IF someone used that full 60 grains- that was not likely to be the most accurate or the safest for the gun. Probably 50 was more typical.

A 357 Magnum will get around 500 ft/lbs ME....but I don't think it's significant. 45 Long Colt is far older cartridge ( for all those cowboy Single Action Army revolvers) and with smokeless loading (typical after about 1890) will get similar energies..as would the similarly-ancient 44-40. Anyway, there would be some other heavy military pistols that could take a heavy load...the 1855 Harper's Ferry .58 cal. Horse Pistol would take a load of 50 grains of powder, and the muzzle energy would therefore have been somewhere near to the Walker.

But there is a huge variety of cartridges and loads to think about, here, and you could easily end up in the weeds on this question, thinking about different aspects. Muzzle energy is not the only important thing, for example- the Walker would have a heavy bullet at lower velocity, the 357 would be a lighter bullet at higher velocity. The .357 trajectory would be flatter, and so be longer range. For Texas Rangers shooting at Comanches, maybe they would have preferred the 357.

Barnes: Cartridges of the World

Gwynne:Empire of the Summer Moon