I wouldn't do a barn style door as they aren't the most soundproof of options. Hard to know from photo how wide the wall is with the box, but could you cover it with framed art?

Barn doors and bathrooms are very bad ideas. You cannot improve on the original swinging door.

You cannot cover the breaker box. It must remain accessible and easy to find in an emergency for safety reasons.

What about painting the breaker box the same color as your wall...and hanging two small pictures vertically on the metal door using magnets :)

If you are going to go for a barn door, I saw this one the other day and it is gorgeous.