I just searched for esp32 projects/libraries on github, the first 3 had malloc calls.

Maybe they don't do[1] dynamic memory allocation in code segments that have real time constraints, or after initialization, etc. (Most embedded projects actually don't have hard real-time constraints, or have them in extremely localized places like bit banging loops...) This is sounds like a good idea and is orthogonal to whether the language's dynamic allocation support is via malloc/free or gc.