At age fourteen, she played four games with the club's U17 team in the Liga dorostu, the Czech second-tier men's U17 league, during the 2019–20 season and recorded a goal.

[1] Šapovalivová stayed with HC Berounští Medvědi U17 as the team was relegated to the Regionální liga dorostu, the third-tier men's U17 league, for the 2022–23 season.

Czech national team teammate Vendula Přibylová was already under contract with MoDo when Šapovalivová signed and joked she would be "starting babysitting in August" in reference to the players' ten-year age gap.

[2] Finishing the 2023–24 season with 29 points in 32 games and making a run to the finals of the SDHL championship series, Šapovalivová was named the league's rookie of the year.

[14] Head coach Carla MacLeod slotted Šapovalivová onto Czechia's top line alongside Kateřina Mrázová and Natálie Mlýnková, giving a tremendous opportunity to the young player.

"[5] The sixteen year old demonstrated herself worthy of the top line role in her first game, scoring two goals and notching an assist in a 7–1 victory over Hungary.

[18] Preliminary game three against Germany saw Šapovalivová open up the scoring with a power play goal in the thirteenth minute of the first period, assisted by Daniela Pejšová and Mrázová;[19][20] Czechia ultimately lit the lamp six times to capture their first shutout win of the tournament and secured placement in the quarterfinals.

"[22] At 2024 IIHF World Women's U18 Championship, Šapovalivova continued her strong play, serving as captain en route to the Czech team's first silver medal at the junior or senior level.