Looking at the source, its a Drupal site. So yes, at its core it is an open source software stack probably with a lot of state-owned templates, themes, and plugins made and/or managed by their contractors. Its fronted by Cloudfront, I don't know if its then being hosted on AWS, some other cloud provider, a state-run datacenter, or a raspberry pi under a desk at one of the DMV offices.
Either way, each DMV and other state agency or agencies in other states is going to want to craft the site in its own fashion for its own "brand". Whether or not this is a good thing is debatable, there's pros and cons each way IMO. You're going to need to have certain kinds of integrations and plugins into byzantine ancient computer systems that each agency also owns and manages. It'll practically never be some quick one-click deploy to make a DMV site; every DMV between all the states are different. They have different forms, different workflows, different database systems for their old systems, different priorities their state legislatures have given them, etc.
Either way, each DMV and other state agency or agencies in other states is going to want to craft the site in its own fashion for its own "brand". Whether or not this is a good thing is debatable, there's pros and cons each way IMO. You're going to need to have certain kinds of integrations and plugins into byzantine ancient computer systems that each agency also owns and manages. It'll practically never be some quick one-click deploy to make a DMV site; every DMV between all the states are different. They have different forms, different workflows, different database systems for their old systems, different priorities their state legislatures have given them, etc.