Saved state for SQL Server Always On on Hyper-V
Since this not production, it's not so critical to do this the "right" way.  Having said that, running QA the same way as production is beneficial for ensuring everything goes well in production.

"Best practices" would be to gracefully shutdown each VM prior to rebooting the host.  That allows the AG to realize the databases need to fail over to the remaining node(s).  You'd also need to do a single host reboot at a time, so the remaining hosts are able to take the load and retain quorum.

Of course, you could just save-state the VMs and let the AG sort itself out - that is after all what high availability is designed to do.