Spagnuolo donned a Santa Clara University Broncos' uniform and was on scholarship his freshman year of college. He currently attends San Diego City College.

Bryson graduated from Fallbrook (Calif.) High School, which is located in northern San Diego County.  Spagnuolo enjoyed a lion's share of success on the diamond mound while at Fallbrook. He went 16-5 in his Warrior career with three saves and struck out 214 batters in 153 innings as a junior and senior in 2014-16. Bryson hit .308 and posted a .509 on-base percentage his junior season. He led the Valley League in wins (11), strikeouts (103) and on-base percentage, and paced San Diego County hurlers in punchouts his latter campaign.

Bryson garnered All-Valley League first-team honors as well as California Baseball Coaches Association All-Southern California State Team recognition in 2016. Spagnuolo has been picked as a Perfect Game USA Underclass Honorable Mention All-American in each of the last two seasons. He has suited up for the Seattle Mariners Scout Team and picked up the win in the Southern California Scout Ball All-Star Game. He played for the SoCal Catch and the Yorkton Cardinals for two summers.

Bryson is the son of Ray and the late Helen Spagnuolo. He has two older siblings, Britton and Spencer. He lives with his father in San Diego. Spagnuolo's hobbies include baseball, baseball, and more baseball. He has volunteered at a homeless kitchen and has set playing professional baseball and pursuing a career as a speech pathologist as long-term goals.