*Club domestic league appearances and goals, correct as of 16:16, 17 September 2024 (UTC) ‡ National team caps and goals, correct as of 8 September 2024
As a youth Kristal began his career with Harju JK before moving to Tallinna Kalev in 2017.[1] In the 2014 Summer Cup held in Pärnu he scored for Harju against Nõmme Kalju FC with the goal being compared to James Rodriguez's 2014 FIFA World Cup goal against Uruguay by local media.[2][3] For the 2021 season he also played for the Estonian under-15 national team in the under-17 league. He scored 17 goals during the season while serving as captain.[4]
In January 2022, Kristal moved to FCI Levadia Tallinn.[5][6] On 15 July of that year he made his senior debut as an 81st-minute substitute for Zakaria Beglarišvili in a 3–0 victory over Tartu JK Tammeka.[7] In the process, he became the youngest-ever player to appear in a Meistriliiga match at 14 years 11 months and 2 days old. The record had previously been held by Andrei Tjunin since 1994.[8][9][10]
On 19 July 2024, German club 1. FC Köln announced that they had signed Kristal, starting from 1st January 2025.[11]
In April 2023 he captained the national under-16 team again, this time for an UEFA under-16 development tournament held in Malta.[15] In June 2023 Kristal scored and assisted on three goals in a 4–2 victory over Lithuania in the Under-17 Baltic Cup, again serving as captain.[16] In Estonia's next match of the tournament, Kristal scored two goals in a 3–3 draw with Latvia.[17]