You will need the Internet both at the exhibition and while walking through the Nuremberg. There are two options – to buy a one-time card, which costs EUR 20-30, or you can use Ukrainian mobile operator roaming options. For example, if you top up your Vodafone account for UAH 500.00, you will receive 500 MB, 500 minutes for calls and 500 SMS & MMS in all directions. For planned calls and navigator application, it will be quite enough.
If you visit BioFach 2019, there is no sense to buy a tourist card in Nuremberg. It gives you only two free trips and two free tickets to the museums, and costs around EUR 28. Spending the same amount you will have a travel ticket for all types of transport.
To plan your meal and a "cultural program" so that at least roughly calculate the amount required, you can use the Internet services for the tourists, forums or guides. Alternatively, you can try to find food outlets offering good prices at www.tripadvisor.ru.