How strong is the explosion?

There's no comparison, Awakened Nekoluga is stronger. Even at level 50, its attack power is only around 25,000, its HP isn't that high, and its fast movement speed means it dies quickly. Plus, it doesn't have a Super Ancient curse debuff, so it's pretty tough in the current meta. It's viable as a disruptor in early stages of old Legends or true Legends, but from the looks of the image, it seems you've finished true Legends too, so you might as well hold off until its third form or talents arrive.