I bought a Pixel 4 and received a Google Nest Hub. It seems that it can be used as a digital photo frame. Since it's a big deal, I'll try to display the grass image on GitHub.

Google Nest Hub settings

Immediately after purchase, Nest Hub will display an art gallery prepared by Google. Change this to a setting that allows you to display your favorite images.

Launch the Google Home app on your iOS or Android device

If you bought Nest Hub, you should have it installed

Go to Nest Hub> Photo Frames

Change the setting of the displayed image to Google Photos

Change the "Organize personal photos" setting to "Real-time shared albums only"

If you do not make this setting, grass images on GitHub will be judged as unsuitable for photo frames and may not be displayed.

Select the Google Photos album to display in the photo frame. The script that will be introduced later automatically creates the album that saves the grass image.

Get access token for Google Photos API

We're going to run a python script that will generate a grass image and upload it to the Google Photos API. To do this, you need to enable the Google Photos API, which is disabled by default, and get an OAuth 2.0 token.

This time, I got the token by referring to this Qiita article.

https://qiita.com/shin1ogawa/items/49a076f62e5f17f18fe5

You will use the Client ID, Client Secret, and Refresh Token later. These are things that should not be published, so please be careful about management.

Script to create and upload grass images

In the following repository, I have prepared a python script that generates a grass image of GitHub and uploads it to Google Photos.

https://github.com/fjt7tdmi/grass-photo

In generating the grass image, I referred to https://grass-graph.moshimo.works/.

When you run the script, a Google Photos album for saving grass images will be created automatically. The default name is "GitHub grass". Please set Google Nest Hub to display this album.

Automation

The repository contains GitHub Actions settings. If you set the following secrets, grass images will be automatically generated and uploaded every day.

GITHUB_CLIENT_ID
GOOGLE_API_CLIENT_ID
GOOGLE_API_CLIENT_SECRET
GOOGLE_API_REFRESH_TOKEN

For those who want to display grass images on Nest Hub

The scripts I made are distributed under the Apache 2.0 license. By forking the GitHub repository, you can use it including automation functions.

https://github.com/fjt7tdmi/grass-photo

However, please note the following points.

Use GitHub's private repository to avoid leaking OAuth 2.0 tokens
I use the secret of GitHub, but this alone is not safe.
If the token is leaked, third parties will be able to view and operate data that is not related to the grass image.
My script does not delete grass images, so be careful about the remaining space on Google Drive
It seems that the API to delete images uploaded to Google Photos is not currently provided (December 26, 2019).
I @ fjt7tdmi will not be held responsible for any direct or indirect damage caused to the user by using this script.

in conclusion

Thanks to @ u_akihir0 for all the advice this time around. Have a nice Nest Hub life!