The Major League Baseball and affiliated Minor League Baseball seasons were cancelled in 2020 due to the pandemic and geographic restrictions across the United States & Canada. However, independent professional baseball leagues played shortened seasons either in their current leagues, with fewer teams, or in "leagues" designed to last only for the duration of the pandemic.
On July 2, 2020 the first professional baseball game was played at Coastal Baseball Park in South Houston, Texas. This was a Pecos League game where the Salina Stockade defeated the Tucson Saguaros by a final score of 16-5. Two games were played each day at the ballpark, and only 4 teams played in the Pecos League that year. The independent American Association played its first games a day or two after the Pecos League.
The second game on July 2, 2020 saw the Roswell Invaders defeat the Houston Apollos by a final score of 5-4.
Confirmation of the scores from these first pro baseball games during the pandemic era are here: https://pecosleague.com/pecosleague.asp?page=68&date=2020-7-1_schedule
Photo credit of the field from 2020 is courtesy of the Pecos League (here). The 2020 rosters, including most of the players in these first pro baseball games that season can be found here: https://pecosleague.com/pecosleague.asp?page=38&year=2020&tablename=pecos_players_2020