Is it possible to download iMessage on a Android? If so, how?

Yes, ofcourse we can download iMessage for PC on android with the help of wemessage emulator here: http://www.imessageforpcapp.com/how-to-use-imessage-on-android-via-wemessage-2019-updated/

Actually, there is not an official iMessage app on Android. However, there still are some methods to get iMessage on Android. Just follow below steps.

Requirements
-An iMessage Account;
-A MacOS Computer running Yosemite (10.10) or Higher;
An Android Device Running Lollipop (5.0) or Higher;
-Java 7 or Higher.

Set Up WeMessage Server on Your Mac

1. Download the client app as well as the server from the developer website.
2. Note you will also need to get Java on the Mac, and enable some specific accessibility features that allow WeMessage to run. To check, you can open a Terminal window and type in the command java. If you get an error message that asks you to download the JDK, then you will have to install it off of Java's website. If you don't, skip this step.
3. Click the website to download the JDK (website:https://www.oracle.com/technetwork/java/javase/downloads/index.html), then you will be taken to Java's website. Click on the Download button under JDK. When you get a page that says something like "Java SE Development Kit Downloads". Click "Accept License Agreement", and then click on the link next to the macOS version of Java.
4. After you get the WeMessage folder, double-click the run. command file to launch WeMessage. If a dialog box pops up about it being from an unidentified developer, you need to go into your System Preferences again, click Security & Privacy, and click General. In the "Allow apps downloaded from" section, hit the button Open Anyway and it should start.
5. Next, In the System Preferences > Security & Privacy screen, click the Privacy, then click Accessibility.
6. You will be asked to enter your iMessage email and a password. Once you enter both of those in, your weServer will start.

Set Up WeMessage on Your Android Device

7. Now you can turn on your Android phone, download and install the WeMessage app from the Google Play Store.
8. Then launch it. Tap the Continue button and tap Allow when a window pops up for permission.
9. To make WeMessage on your Mac to connect with the app on your Android, you need to set your Mac's IP address. (Note: the IP Address points to where your weServer environment is running and it is needed in order to connect to your weServer.) There are two types of IP addresses: a private IP address and a public IP address. A private IP address allows you to connect to your weServer inside your own Internet network. While you want to connect outside of your own Wi-Fi and access your weServer over a cellular connection or outside your home, you will need a Public IP Address.
10. Let's get our private IP address first. Go to System Preferences and then click Network. Then click Advanced... and then click the tab that says TCP/IP. Your private IP address will be next to IPv4 Address.
11. Later, you can enter your IP address into the corresponding field. You are supposed to press Sign In, and you will see a checkmark animation and get into the main screen. Finally, you get iMessage on android with WeMessage successfully.
To access your weServer outside of your personal Wi-Fi network, you need to port forward. Almost every router or modem brand has a different method for port forwarding, you can check countless guides and tutorials on the Internet that explain the process. When someone asks you how to get iMessage on Android, you may ask him to try this method.

For more methods, check: How to Get iMessage on Android

No Imessage is for Iphones.