Deploying SSRS reports on an "Air Gapped" report server without SSDT?
You could use a RS.exe script. This would allow you to create a script, a batch file and a set of .rdl files.
Then you just call rs.exe with the script you created to upload the files to the report server.

You can find an example here

There is also a tool called rsscripter.exe created Jasper Smith, a SQL Server MVP.
Apparently it is now included in finebuild and the zip is still archived. See this link for the original article.