A kirana is a speed problem and a count problem. The same eight items are half the day, and the oil tin is either there or it is not. A system that makes you search a catalogue for "soap" while a queue watches is the wrong system.
What to set up
Put the fast items where the thumb already is. Keep one stock count, shared by the counter and any order that comes in on the phone, which is the point of the inventory guide. A loose item sold by the packet is a product. A loose item sold by the kilo needs a price per kilo and a quantity, not a new product every time the scale moves.
Most kiranas are under the VAT line for a long time. Goods cross into mandatory VAT above NPR 50,00,000 of taxable turnover in the past twelve months, on the Act as amended for this year. Until then the bill is a PAN bill if you have a PAN, and it should not grow a 13 percent line. Read PAN versus VAT before you copy a neighbour's bill.
The machine is a phone or a tablet. The printer, if the lane wants paper, wants to be wide enough for a shop name and three lines. That is 80mm, and it was not more expensive than 58mm in the listings we opened. The same counter shape for other trades starts at clothing.