How would he fit on the San Antonio Spurs?
Jackson could theoretically compete for the Spurs' backup center role next season, as Jakob Poeltl will surely still be the superior defender (for now). He is still unrefined enough to warrant spending time in the G-League with the Austin Spurs. It could take him a full season before he’s ready to join the rotation and carve out a role for himself off the bench.
If he were to eventually come off the bench, he would provide the Spurs with a talented shot-blocker who, along with Poeltl, would ensure that the team had a rim protector on the floor at all times. Additionally, his hustle and high-energy play could help energize the Spurs bench much like how Keldon Johnson does for the starting lineup.
Additionally, when paired with a good passer like Tre Jones, he could excel as an athletic rim-runner and add a new dimension to the Spurs' offense. Assuming his shot-blocking skills translate to the NBA and he improves his offense, he could eventually prove himself to be good enough to take Poeltl's spot in the starting lineup.
Drafting Jackson could be a worthwhile gamble for the Spurs given his very high ceiling on defense, but he isn't quite a sure thing. Even with his potentially game-changing defensive abilities, it could take several seasons for him to reach his full potential, and it would entirely hinge on his development on offense. If he can even develop an average offensive skillset, though, he could become a very interesting two-way player in the Spurs' frontcourt. Ultimately, I think he'd be an excellent choice for the Spurs at 12.