Wallace attended Greenbrier High School in Greenbrier, Arkansas. As a freshman in 2017, he hit .349 with four home runs before batting .481 with 11 home runs as a sophomore in 2018.[1] As a junior in 2019, he batted .514 with six home runs and 22 RBIs.[2][3] That summer, he played in the Under Armour All-America Baseball Game at Wrigley Field.[4] His senior season in 2020 was cancelled after eight games due to the COVID-19 pandemic, but he was still named the Gatorade Baseball Player of the Year for the state of Arkansas.[5]
Wallace went unselected in the 2020 Major League Baseball draft and enrolled at the University of Arkansas to play college baseball for the Arkansas Razorbacks. In 2021, as a freshman at Arkansas, Wallace started sixty games (mainly in right field) in which he slashed .279/.369/.500 with 14 home runs, 44 RBIs, 11 doubles, and a team-leading 67 hits.[6] His 14 home runs were second on the team behind Robert Moore and also tied the freshman home run record set by Heston Kjerstad.[7] He was named a Freshman All-American, making him the 24th Razorback to earn the honors.[8] After the 2021 season, he played collegiate summer baseball for the Bourne Braves of the Cape Cod Baseball League.[9][10][11][12] For the 2022 season, Wallace moved to third base.[13] He was named the Southeastern Conference (SEC) Player of the Week on March 15 after he hit three home runs (two grand slams) and had 13 RBIs over a weekend series.[14] Over 65 games, he batted .297 with 16 home runs, sixty RBIs, and 19 doubles, and ended the season as a top-40 prospect for the upcoming draft.[15]