Hi, only 4MB of space is allocated for heap: openmv/boards/OPENMV4P/omv_boardconfig.h at master · openmv/openmv · GitHub
When you pass load_to_fb=True though we allocate the model in something called the fb_alloc stack which is 11MB: openmv/boards/OPENMV4P/omv_boardconfig.h at master · openmv/openmv · GitHub
The hardware does support float32, however, you are running out of RAM. You need to make the model smaller. Otherwise, you are welcome to modifying the heap/fb_alloc stack sizes in the firmware given the two variables I mention to increase the heap. Note that you will have to take RAM from other buffers to increase the heap size.