Using Google Sound Picker on any non-Pixel device

1. Download and install Google Sounds Picker from Google Play Store or APKMirror:
- https://play.google.com/store/apps/details?id=com.google.android.soundpicker,
- https://www.apkmirror.com/apk/google-inc/sounds/,

2. Download and install Activity Launcher from Google Play Store or GitHub:
- https://play.google.com/store/apps/details?id=de.szalkowski.activitylauncher,
- https://github.com/butzist/ActivityLauncher,

3. Run Activity Launcher and search for SoundPickerActivity, click this option and then Start Activity.

4. Wait a while until all sounds are show up. Now, after choosing any of category, tap on any sound and use save option in the right corner.

5. Now go to your device setting and try to change the new notification sound by finding it on the list (new sounds will shop up with the same names as in Sounds Picker, even if they are displayed in your device's default language). Now, select the new sound and set.

You can delete added sounds in Google Sounds Picker by using trash icon on the list with all of sounds.

Source:
https://www.youtube.com/watch?v=K7ucInG2NYI