Wow, thanks for the direction! Yes the H7 uses the same mbed core with nano33ble. The ArduinoCore-mbed already supports the H7. Appreciate any direction on how to adapt the platform.py. 
Below is my current h7.json. Looks like you’re pointing to exactly where I need to change platform.py.
KeyError: “Invalid board option ‘build.variant’”:
{
"build": {
"cpu": "cortex-m7",
"extra_flags": "-DSTM32H7xx -DSTM32H747xx",
"f_cpu": "480000000L",
"mcu": "STM32H747XIH6",
"product_line": "STM32H747xx"
},
"connectivity": [
"wifi",
"bluetooth"
],
"debug": {
"default_tools": [
"jlink"
],
"jlink_device": "STM32H747XI",
"openocd_board": "st_nucleo_h743zi",
"openocd_target": "stm32h7x",
"svd_path": "STM32H7x7.svd"
},
"frameworks": [
"arduino",
"stm32cube",
"libopencm3",
"mbed"
],
"name": "H7Portenta",
"upload": {
"maximum_ram_size": 1024288,
"maximum_size": 2097152,
"protocol": "sam-ba",
"protocols": [
"jlink",
"cmsis-dap",
"stlink",
"blackmagic",
"mbed"
]
},
"url": "https://www.arduino.cc/pro/hardware/product/portenta-h7",
"vendor": "Arduino"
}