The Google Play Store comes pre-installed on all Rumie tablets, which includes the Google Play Protect security suite that functions autonomously in the background. Google Play Protect will scan Play Store apps for any potential malware.
Although Rumie tablets function offline, the Google Play Store will have scanned all apps for potential malware prior to downloading. As long the respective apps are downloaded from the Google Play Store and using friendly content online, there is little risk in the tablets getting a virus.
For more information on Google Play Protect please review Androids official documentation on it: Google Play Protect