Do I need to go full AP to deal damage as Malphite/Maokai?

Malphite and Mao do shiit tons of dmg even when going Tank Full Fuking Tank

Malph in particular gets scalings with armour, so can do decent damage building full tank.

I don't personally play mao, but I'm pretty sure he can do decent damage with just tanky-ish ap items like roa and abyssal.

That said though, both of those champions are generally going to be playing the role of a tank, doing damage with them should not be a particular priority.

no. They have pretty reasonable base damages; Maok can nuke squishies with only ~200 AP.

If you want to deal damage with those the combination on ROA, Abyssal and Sunfire can work very well together. They work as tank items while retaining good damage as you get to increase your sunfire damage through abyssal mr reduction which allows amplifies your other skills.

well apparently thunder lords is amazing on maokai don't ask how it was just a happy accident i was able to get 3 kills on a trundle before he killed me once and one of those was a first blood granted i don't know his skill level but i don't want to know, it felt good

You'd still want to take standard tank masteries with grasp. I mean thunderlords can work but in the end you don't build enough damage to justify it and you're not gonna one shot anything. You will chunk people's health though pretty well while still being tanky though.

you can grab abyssals or zhonyas

is your best friend.

That's good enough to rip squishies apart while still going the rest of your inventory full tank.

Maokai needs just and for AP items Malphite needs just and maybe if you're that guy.