Most trips to Belarus start at Minsk National Airport. The smart move is to install the eSIM at home before you fly, then turn on data when you land. Your phone finds life:) or MTS on its own and you are online before you reach the taxi rank.
Minsk has the best signal in the country. life:) runs 5G here, and 4G is fast across the center, the metro stations, Independence Avenue, and the train hubs. For a short city break the 1 GB for 7 days plan at $2.80 covers maps, messaging, and the odd photo upload. If you stream or video call a lot, step up to the 3 GB for 15 days plan at $7.49.