2) Jonas Valanciunas
Center Jonas Valanciunas is a physical big man who is set to become an unrestricted free agent this summer. Valanciunas is known for his production, capable of scoring both inside and out and crashing the glass, though he hasn't been as productive this season for the New Orleans Pelicans.
At 32 years old, his time as a full-time starter in the NBA may be coming to an end but he could still be a useful spot starter or a backup big man. Especially if the Spurs decide to move on from Collins during the summer. Having a veteran big man with plenty of experience, size, and skill would be useful, particularly after injury issues with each of San Antonio's centers this season.
San Antonio may instead prefer to roll with Bassey and Barlow as the backups to Wembanyama, with them occasionally sharing the floor with him, but Valanciunas would add floor spacing. He isn't a knockdown shooter from deep but he can knock down enough to help justify signing him over other big men who hit the open market. Especially if he is willing to take a steep pay cut at this point in his NBA career.