"This is in the purple box" perhaps ?
(or does that miss some nuance or distinction in בתוך ?)
Not here, I think. Some distributional difference. You probably wouldn't see 'inside Africa' very much. Choosing between 'in' and 'inside' is probably a decision to slightly increase the emphasis on enclosure.
But something can be either in or inside a box without real shift in implication. I wondered whether there was stronger choice in Hebrew between בתוך and something else - perhaps implying tighter or more complete enclosure – perhaps to the point of invisibility or something ?
(If not I would probably suggest accepting in here)