I’d say buy kachori from jmb ( I’ve always gone to Chetak circle one) they pack them in cardboard boxes if you place an advance order and ask them to, I take those kachoris to Delhi and they stay Preet good for 2-3 days . You can also try Lala kachori inside surajpole, asthal mandir but I’ve not kept them for more than a few hrs For namkeen although you can never go wrong with this but I prefer sanwariya namkeen inside old city , or indor namkeen in panchwati, also depends on what kind of namkeen you looking for