I have created a project that match windows build version to a manifest, enabling you to download the manifest for your specific build, download all the pdb's and take them to the isolated network.

Repo - https://github.com/ErezAmihud/WindowsSymbolsByVersion

Website - https://erezamihud.github.io/WindowsSymbolsByVersion/

NOTE: if the windows version you use is not there, open an issue and I will make it a priority.

Also, if you have the exe of your specific build, you can extract it, extract the install.wim (sources/install.wim) and then run symchk on those binaries.