My experience is with on premise setups so my comments focus on that.
I think you can create an Availability Group with just one Windows Server however it will limit what you can learn.
As far as I know Sql Server 2016 requires a Windows Server Cluster. In later versions of SQL Server there are other options (Linux is one).
Assuming you require a Windows cluster then one thing to consider is that you need to be using a Server operating system to be able to create the Cluster. I think, in theory, you could use 2 PC's if they have Windows Server on them.
If you only want to test for a few months then perhaps one option is some Virtual Machines with Windows Server evaluation licenses from Microsoft? You will need to check the license requirements to see if you can use them in your situation.
If you don't have a domain you can add test configurations to then you may need a third machine/VM for a domain controller. I found that I couldn't get the domain controller and SQL Server to run on one Virtual Machine but that could just be my mistake. My knowledge of domain controllers and active directory is limited.
There is likely to be suitable cloud options but I'm fairly new to them myself so I'm wary of recommending anything.