Spigen Rugged Armor Designed for Nintendo Switch 2 Case (2025) Protective Handheld Case with Ergonomic Grip and Strap (Not Compatible with Switch Dock) - Matte Black

You might benefit from a case that is one piece for the whole system, because it should keep the joycons from flexing and losing connection. Something like this one is an example (there are others). If being able to dock without removing the case is important to you then you'll need to find one that can do both.