A question about dialogue boxes!

I'm new to both coding and Pico so bear with me, maybe there's no right answer but would appreciate suggestions.

Say you have a standard type of RPG game with a character who moves, and you approach or talk to an NPC, triggering a dialogue box on top of what's already on the screen (just like any old pokemon or dragon quest game). What would be an efficient way to do this? Load a new scene but don't clear the screen? Disable the player character's movement and actions while a list of text cycles through?

I've made a clunky textbox function (see image) but there must be a better way.

Any ideas or links to successful examples would be great.

Thanks in advance to anyone who answers!