Born in Burundi, Berchimas moved to the United States as a child, settling in High Point, North Carolina.

[2][3] He played eight matches with Charlotte's MLS Next Pro reserve team, Crown Legacy FC, during the 2023 season.

[5] Having already represented the United States at under-15 and under-16 level, Berchimas was called up to the nation's under-17 side for the 2023 FIFA U-17 World Cup.

Despite being the youngest player in the squad, he started the United States' campaign with two goals in a 3–1 victory against South Korea.

[7][8] He followed this up with a goal in the United States' 2–1 win against Burkina Faso, taking him joint-first in the tournament's goal-scoring chart.