Well, I tried to do a skinny wall cabinet with a door, but was forced to choose between storage and hiding the electric panel. My 2nd try was a curtain to hide the panel, got stymied by fire risk. Now of course, I have 2 young cats who would try to climb the curtain. I gave up and left it open. It's ugly but oh well. So are the water heater and furnace.
Haven't even tried anything with the sump pit at my parent's house. The only decent thing I can think of is to make it a walled area, but their pit location makes that impractical.
Honestly, given your setup, I'd just make it a "closet". Walls and door.