Grünberg was born on 2 September 2000 in Tilburg. His father is from Indonesia.[2] His mother and grandmother worked as gymnastics coaches, which is how he started the sport. He moved to Den Bosch when he was 18 years old for his gymnastics training and chose to not go to university.[3] He is a fan of the Willem II and Real Madrid football clubs.[4]
Grünberg missed the 2021 European Championships because of a torn ligament in his ankle. At the 2021 World Championships, he dislocated his finger in the middle of his parallel bars routine. Despite this, he still finished the competition and placed 38th in the all-around.[4]
Grünberg won the all-around silver medal at the 2022 Dutch Championships, losing the gold medal due to a fall on his still rings dismount. In the event finals, he won the gold medal on the parallel bars, the silver medal on the floor exercise, and the bronze medal on the pommel horse.[8] At the 2022 European Championships, he competed with the Dutch team that placed 11th in the qualification round.[9] He then competed at the 2022 World Championships in Liverpool where the Dutch team finished 13th in the qualification round. He also did not qualify for any of the individual finals.[10]
Grünberg won his first FIG World Cup medal at the 2023 Varna World Challenge Cup with a bronze medal on the parallel bars.[11] He also placed seventh in the horizontal bar final.[4] He was initially the first reserve for the parallel bars final at the Osijek World Challenge Cup, but he was able to compete after a withdrawal and placed seventh.[12] At the 2023 World Championships, Grünberg and the Dutch team placed 11th in the qualification round and earned a team berth for the 2024 Olympic Games.[13]
