Char Jackson wrote:

The reason I asked in the first place is that I have about two dozen
Win10 VMs, and counting, and it seemed a shame to get updates for each
of them separately. I guess that's how it needs to be, though.

That's what I use WSUSoffline for. I run it to create a repository that
I could network to or tote around on a USB flash drive (to, say, mount
in your VMs). I have WSUS offline retrieve updates for several
products. Looks like the W100_x64 is for Windows 10 x64 and it's about
9 GB in size.