This question may sound naive but any pointers would be appreciated.
I have to integrate playstore reviews with slack. I could do it easily for AppStore because AppStore was already present in IFTTT. However, I am unable to do it for Google Play Store as it is not available. Is there any way I can create it?
By "AppStore" I guess you actually mean the Apple App Store, which indeed has a service in IFTTT, which you can use to easily connect it to Slack.
By "any way to create it" I am guessing you mean if its possible to add the Google Play Store as service to IFTTT, so that you can connect it in the same easy way with Slack. To my knowledge that is only possible for the owners of the service (so Google in this case), so the short answer is no.
However, you can integrate your own services with IFTT through webhooks, which would require the Google Play Store to support sending information to webhooks. I don't know if that is possible with Google's Play Store, but it would be something worth investigating.
What would definitely work is to create your own Slack app (instead of using IFTTT) that is querying the Google Playstore through its API and then sending the information to your Slack as needed.