Is it possible using the Microsoft.SqlServer.DacFx.x64 nuget package to query out the list of SQLCMD Variables from a dacpac file?
Since there is not much activity here: don't know if DacFx can do this, however DACPAC file is a ZIP archive containing model.xml which is the whole body of SSDT project. Unzipping and extracting values can be automated.
SqlCmdVariables in this XML file look like shown below:
XPath would be //Header/CustomData[@Category='SqlCmdVariables']/Metadata/@Name