Yes, that won’t, but the other solution, to specify the path in the Deploy to Bitrise.io step (instead of just a directory) certainly does 
The Sign APK step exports the signed APK’s path in both BITRISE_SIGNED_APK_PATH and BITRISE_APK_PATH env vars:
So setting the Deploy directory or file path (deploy_path) option of the Deploy to Bitrise.io step to e.g. $BITRISE_SIGNED_APK_PATH should deploy only the signed APK and expose its public install page (similar to what’s described here Public install page URLs for multiple apps).