How to optimize Unity 2D mobile games for low-end Android devices?

[SavannahPB]

I'm an indie developer working on a 2D mobile puzzle game in Unity, and I'm hitting significant performance issues on older Android devices. The game runs smoothly in the editor and on newer phones, but it suffers from frame drops and increased battery drain on lower-end hardware. For developers who have optimized for a wide range of devices, what are your top mobile game optimization tips for reducing draw calls and managing memory in a 2D context? How do you effectively profile and identify bottlenecks on actual devices, and what specific Unity settings or asset pipeline steps made the biggest difference for you? Are there common pitfalls with UI systems or particle effects that I should scrutinize first?