Hi there! I have never converted STEEM into hryvnia, but I have converted other cryptocurrencies. I don't know if this is the best way, but I do it like this:

• I use the online currency exchange (https://24bestex.com/exchange_USDTERC_to_P24UAH/, https://ukr-obmen.com/exchange_USDTERC_to_P24UAH/ or other);
• I choose the cryptocurrency that I need to convert into hryvnia;
• I choose Privat24 (this is an online banking service from my bank);
• I convert cryptocurrency and money immediately comes to my account in hryvnia.