Most people wish to have majority of the items to be compatible to their own needs, however there will be a number of items that will not meet their needs. There is a limitation for Joyplay to allow user to be able to run application that normally not available for Android system. There are other possible ways you could be able to try this VN without having some major concerns. Here are few possible ways:
1. Accept the risk, download and execute the application * recommend to have at least one antivirus program to scan the files.
2. Setup a virtual machine and put the application in there to execute
3. Use an older computer that is not being use as much, execute the application
4. Could buy a cheap computer, since number of computers become cheaper over the years. Most VN can run on low end computers without any major concern.
* There are other alternate ways to test application if you do not want to run it on your daily system.
Regarding to system virus (there are so many types of virus), it a risk for anyone to get it on their devices (Windows, Linux, Unix, MacOS, iPadOS, iOS, Android, and other operating system). If you are not comfortable with the application or site, then don't execute the program or go to the site.
You are not the only one who do not know much about computers and/or smart devices. You may want to reach out to the developer if they could check if their application could support android or so. If I understand correctly that Unity could be supported in multiple operating systems. I have some application on android and iOS devices that supported by same vendor's application. If not, then keep eye out over time, maybe there may be someone who may have converted this VN to Joyplay or have step by step process how to convert it yourself.
Have a great day and be safe...