If I'm not mistaken, that's roughly 18x10x20 (inches) or roughly .96 square feet of grow space, or roughly .3 square meters

I guess my big alarm bell would be that my 7" seedlings would barely fit, and if put directly into bloom would yield about 5 grams in about 8 weeks

which I'd go through in 2 blunts, or 10 bowls

So my alarm bell would tell me "DING DING DING - We have a waste of cash!"

I can see it as a novelty item with a plexiglass window - but as a secret grow box? If you need something small, try one of those ikea like linen closets, or heck, a tv/radio box