my son is not type c but goes to SJKC.
he plays Roblox with his friends, all the while with whatsapp audio on.
so they converse in Mandarin.

i prefer not to let him play too much, but he really practices his Mandarin (effortlessly) when he plays.

at least i know his friends, who he is playing with.
he uses live chat (speech to text) a lot as well when not playing with friends.
hard to monitor, but trying my best.