Today's Sonic Central stream didn't give us a release date for Sonic Superstars, but it did reveal a new Lego DLC.
Sonic Superstars
SONIC SUPERSTARS for Nintendo Switch - Nintendo Official Site
Sonic Superstars is getting a Lego DLC, but still no release date
Sonic Superstars & Sonic Frontiers DLC Release Dates Set in Trailers, sonic frontiers dlc
Sonic Superstars Digital Deluxe To Include Prototype Rabbit Skin, Mecha Sonic, LEGO Fun Pack - Games - Sonic Stadium
Dr. Eggman officially joins Lego Sonic's second wave of releases in August
Unboxing SONIC SUPERSTARS - Nintendo Switch Bonus DLC Lego Eggman (Indonesia)
Standard & Physical Copies of Sonic Superstars Can Be Upgraded To Digital Deluxe - Games - Sonic Stadium
Sonic Superstars [Ryujinx Nintendo Switch Emulated Release] (v1.0.5A + LEGO Sonic Skin DLC, MULTi8) [1.5GB] / Outpath (v1.0.2, MULTi20) [419MB] / Valor & Victory (Build 12391632, MULTi6) [688MB]
Sonic Superstars: Characters, stages, DLC, and everything confirmed