Out in the open, if an army has multiple heroes, and you click "Equip" on that army, it opens main hero's screen. With left/right arrows surrounding hero's name allowing you to navigate to other members of the army.

In a city, if you click on a hero, then click "Equip", the arrows are missing. To examine all the units in that city, you have to close the current one, then select another one. Then "Equip" again.

Idea: treat the units in the city as if they were an army. Cycle thru them the same way you do in an actual army, that is not in a city.