Signing Nativescript Play Store release with .der file

In the Google Play console > Release Management > App Signing

It provides 2 files: (App signing certificate) and a (Upload certificate).

Both are .der files.

The page also provides the file MD5, SHA-1, and SHA-256 fingerprints.

I found this section of the docs that explains how to use a .keystore file. https://docs.nativescript.org/tooling/publishing/publishing-android-apps#build-signed-release-apk

As well as this thread: https://discourse.nativescript.org/t/new-google-play-app-signing-workflow/5271/4

The thread states that .der files can't be used with Nativescript.

Is it possible to sign a release APK with the .der file?

Is it possible to build a Nativescript release APK without depending on Android Studio for a .keystore?