outlet next to breaker box
Go ahead -- although you may have to run THHN through the nipple from the panel

Coming out the side of a panelboard is a nothingburger under the NEC under most cases.  The reason why you're confused is you're thinking this whole assembly is a protective sleeve under the 312.5(C) exception, which requires the sleeve come out the top, when it really isn't as the receptacle box interrupts it.

The easiest way to dispel any confusion is to use short lengths of THHN in the nipple for the home run, if you will, and then run the NM from the first receptacle up the sleeve from the receptacle box to wherever it needs to go.  This bypasses 312.5(C) and its rather limiting exception altogether.

Just remember to use a conduit-to-NM transition fitting (EMT-to-NM transition fittings are standard parts) on the free ends of the conduit sleeves.