Nits:
Container / form backgrounds should be lighter than the app background. It's just how the human eye perceives depth. Closer object should be lighter. Dark foregrounds are harder on the eyes.

It seems like the "Next npub" container has no margin-left. Viewing on mobile. The container licks the left border of my screen. Feels like it should be centered.

This tool is fucking awesome 🚀 Thank you Pablo! 

 Shouldn't be used on a mobile in the first place I guess