Submitted: 22 September 2026 Posted: 23 September 2026 You are already at the latest version Microalgae are emerging photosynthetic chassis for sustainable bioproduction and biological research. Yet, relative to plant and animal systems, their development as broadly engineerable platforms remains constrained, with many advances still limited to organism-specific or compartment-specific demonstrations. This review asks why this gap persists and how it may be closed.