KeystoreHelper.getSigningCertificatePublicKeyBase64(context)
и возьми значение из логов (Base64 без переносов).
keytool -exportcert -rfc -keystore /path/to/keystore.jks -alias YOUR_ALIAS | openssl x509 -pubkey -noout | openssl pkey -pubin -outform DER | base64
androiddebugkey, пароль: android
keytool -exportcert -rfc -keystore ~/.android/debug.keystore -alias androiddebugkey -storepass android -keypass android | openssl x509 -pubkey -noout | openssl pkey -pubin -outform DER | base64
keytool -list -v -keystore /path/to/keystore.jks -alias YOUR_ALIAS
printf "%s" "PUBLIC_KEY_HEX" | xxd -r -p | base64
apksigner verify --print-certs /path/to/app.apk
apksigner verify --print-certs /path/to/app.apk | awk -F': ' '/Signer #1 certificate:/ {p=1} p && /Public key/ {getline; print}'