Actually Intel provides a software to utilize a RPi4 as backend, to make your camera available in your network and directly use all API commands: https://dev.intelrealsense.com/docs/open-source-ethernet-networking-for-intel-realsense-depth-cameras
FRAMOS has a similar middleware for their reference models:
D435_Manual_V1.1 - Page 24
By default, the Pi 3B will not boot from flash drives.
Create a working SD card with Raspbian Buster Lite first then boot from this SD card first. When you are at the command prompt run
echo program_usb_boot_mode=1 | sudo tee -a /boot/config.txt
Once the reboot is complete, run
vcgencmd otp_dump | grep 17:
You should get ** 17:3020000a**. ...