Most focuses are held.

Not always, for instance some clerics can use a shield as a focus. But if you are using a focus, you will need to be holding it. This is not true for a component pouch.

You can hold a focus in the same hand as you do your somatic components

A spellcaster must have a hand free to access a spell’s material components—or to hold a spellcasting focus—but it can be the same hand that he or she uses to perform somatic components.

You don't need to hold a component pouch

You can just have it on your belt and reach in to grab what you need.

You cannot sheath weapons and draw weapons in the same turn

At least, not without using an action. You get one free object interaction each turn. This can be sheathing a quarterstaff, or it can be drawing a dagger. To do both, you must use an action. The good news is that he probably doesn't need to do this. You can hold a staff one-handed while you're performing a spell.

Most focuses are held.

Not always, for instance some clerics can use a shield as a focus. But if you are using a focus, you will need to be holding it. This is not true for a component pouch.

You can hold a focus in the same hand as you do your somatic components

A spellcaster must have a hand free to access a spell’s material components—or to hold a spellcasting focus—but it can be the same hand that he or she uses to perform somatic components.

You don't need to hold a component pouch

You can just have it on your belt and reach in to grab what you need.

You cannot sheath weapons and draw weapons in the same turn

At least, not without using an action. You get one free object interaction each turn. This can be sheathing a quarterstaff, or it can be drawing a dagger. To do both, you must use an action or drop the original item. The good news is that he probably doesn't need to do this. You can hold a staff one-handed while you're performing a spell and then hold it again in two hands once the spell is complete.