HyperV shared virtual disk

Solution 1:

As mentioned, you can't use shared VHDX in W10 VMs simultaneously. The best way would be deploying a File Share, which will be accessed from your VMs. Since you have 2 nodes, you can deploy Failover Cluster with either S2D or StarWind VSAN and then configure HA File Share on top (in case you need high availability). The following guide covers the configuration: https://www.starwindsoftware.com/resource-library/starwind-virtual-san-for-hyper-v-2-node-hyperconverged-scenario-with-windows-server-2016/

Solution 2:

Sharing a file system not intended for active/active cluster usage between multiple machines will cause problems if you ever get it to work.

A file share is the correct solution for your use case. If you need higher performance, install a higher-bandwidth network and secondarily switch to faster storage.