Android App Signing Assistance Required with --------- Play App Signing

I am currently struggling with the sign-in process for an Android app and require some technical assistance, preferably from an experienced App Developer or someone possessing high-level proficiency in Android app sign-ins.

Critical Points:
- My app is designed solely for Android devices.
- Unfortunately, I do not have the key store password for the app.
- Furthermore, I am looking to utilize a distinct sign-in method that does not involve APK Signature Scheme or JAR Signing.

Ideal Skills and Experience:
I am seeking assistance from a freelancer who has:
- Extensive experience with Android app development.
- A proven track record of successfully managing app sign-ins on the Play Store.
- An understanding of different app signing methods beyond APK Signature Scheme and JAR Signing.
- The ability to deliver a solution effectively and relatively quickly.

This is your chance to prove your skill and knowledge in Android app development, by providing an efficient solution to my current problem.

need to sign with play app signing key not with jsk