I found the solution myself, I'm posting it because it may be helpful for someone else.
For Android only, I didn't try for iOS/iPadOS yet.
Android
- In Android Studio create a new Image Asset 
(File > New > Image Asset); 
- copy the just created asset folders somewhere in your cordova project;
 
- in config.xml file use 
resource-file tag to copy the assets in the specific Android project folder (see Cordova documentation). For example: 
<resource-file src="cordova_app/icons/android/mipmap-xxxhdpi/company_logo.png" target="android_app/src/main/res/mipmap-xxxhdpi/company_logo.png" />
- create a file named 
styles.xmlin your Cordova project and like the previous point copy this file in 'src/main/res/values' folder using resource-file tag;
The XML file should be something like this:
 
<?xml version="1.0" encoding="utf-8"?>
<resources>
    <style name="SDKBaseTheme" parent="Theme.AppCompat.Light">
        <item name="awsdkSplashBrandingIcon">@mipmap/company_logo</item>
        <item name="awsdkLoginBrandingIcon">@mipmap/company_logo</item>
        <item name="awsdkApplicationColorPrimary">@color/color_awsdk_login_primary</item>
    </style>
</resources>
- launch the 
sencha app build android command to check the result