It's mostly high margin vegetables and spices. Look up gotham greens for a successul and properly done indoor ag startup.
Generally tomatoes and maybe peppers have enough margin and volume to be justify indoor settings.
Things like nuts are a no-go or any sort of wheat/cotton/maize/soybean operation (even specialty applications like edamame have severe uphill battles to profitability)
Massive amounts of government regulation that inflates the price.
I.e. just weed so far.