My project is currently based on the MAX32630FTHR board that also has an SD-card slot.
I am logging data at about 500Hz sampling rate that yields up to 100MB data per day.
Turns out that board has an SPI implementation that impacts the transfer rate quite much (~70 KB/sec), thus data transfer takes hours if i connect that board to my PC (USBMSD).
However if i remove the card from the board and put it directly in the pc, i can copy the same amount of data in just some seconds… This is a huge bottleneck in real IoT as we either have ease of use (card does not need to be removed from the IoT device) or great transfer speed but that needs a different HW design as the sd card needs to be removed to copy the data
So i wish you will end up with an SD (and not SPI) implementation