Hey,
I’ve recently removed Windows 10 OS from my laptop and made the full switch to Ubuntu. But when I was installing Ubuntu I accidentally overwrote my Windows 10 OS which has EVERYTHING so I need to re-publish my app on the Google Play Store. Is there a way I can build my release here on Ubuntu or will I need a Windows? Because, I don’t think Ubuntu has/uses the zipalign/signer, etc.?
Sure it does. The Android build tools include zipalign and apksigner. If you don’t want to install all of Android Studio, you can install them easily with sdkmanager.
If you lost your keystore, you have a problem. I hope you still have it otherwise you might have to contact the Google support or create a new application identifier and app on googleplay.
Edit: seems like you do have lost it.
I suggest contacting the support first before re adding the app, they might be able to help you.