There are few parts that might need to updates in order to work out this part:

1. keras:

I had problem to import keras when in python3. Then I find out that tensorflow is installed from puwheels, and it only installs 1.14.x. However, you will need to have tensorflow 2.0.0 or up. This post helped me to find the solution: https://github.com/tensorflow/tensorflow/issues/37355

You need to install binary directly, and I did 2.4.0. Also have a check on which python version you have to install:

https://github.com/lhelontra/tensorflow-on-arm/releases

I did:

pip3 install https://github.com/lhelontra/tensorflow-on-arm/releases/download/v2.4.0/tensorflow-2.4.0-cp37-none-linux_armv7l.whl

2. edgetup:

If you have edgetpu error, it is because its deprecated. Right now it is updated to PyCoral. So any calls from edgetpu wouldn't work. It means at 2021 July, the Install TensorFlow for EdgeTPU section is not going to work.

I resolved it by following coral instruction here step by step:

https://coral.ai/docs/accelerator/get-started/

Since the demo object detection app coco_object_detection.py is still using edgetpu, and you do not have it. So it will give you error such as Module not find error since there is no edgetpu module for PyCoral api. You could check whether you have it by running this:

python3 -c 'print(__import__("edgetpu").__path__)'

Likely it is not even installed. You could follow code example here by installing libedgetpu1-legacy-std

But I decided to use PyCoral instead. It means you need to run a different demo supporting PyCoral. Check out the camera examples at the bottom:

https://github.com/google-coral/examples-camera

I use the openCV example they have to make my camera work.