Electrical – NM cable from wall box to dishwaster

Yes, you are right. Current code wants the dishwasher GFCI protected. However, unlike the dishwasher, there is no specific article that explicitly states a disposal requires one.

A Double pole GFCI 20 Amp breaker can protect two individual appliances. The Wiring is known as a MWBC "multi-wire branch circuit" and uses 12-3 "Black, Red, White, and Ground".

However, current code also wants everything in a kitchen, including dishwashers to be ARC-fault protected. One solution is to use a Double-Pole Dual GFCI/ARC fault 20 Amp breaker.

But since you ran two separate branch circuits I don't think code allows you to combine the neutrals as one in the panel because the conductors are not in the same sheath/raceway when they leave the panel. In which case, you would just do as you mentioned using a 2-gang box with one GFCI and one regular outlet, which is probably far way less expensive!

I recently remodeled my kitchen, and the original wiring was just two romex's coming out of the wall and hardwired to the dishwasher and disposal respectively. There are wiring enclosures on each appliance. Evidently that was acceptable in times past.

I'm sure our more knowledgeable contributors will come by and cite the current code.

I decided to go with installing a wall box for each circuit, and installing a single 20A receptacle for each (assuming they are 20A 12g circuits). This allows you to simply and definitively disconnect either when doing any servicing. It's simple, safe, and straight forward.

You can get an appliance plug that wires into the disposal at the store. My Bosch diswasher came with a power cord that terminated in a supplied plastic surface mount box. I put that under the sink and connected an appliance rated cord and plug to it.