Offline air-gapped "freebsd-update fetch"

[Chris Stankevitz]

How can I perform/simulate a "freebsd-update fetch" on an air-gapped
disconnected offline computer running FreeBSD-10.1-RELEASE?

===

I tried (from some advice given 7 years ago):

1. "freebsd-update fetch" from an online machine running
10.1-RELEASE-p12.  FYI the command responded with "No updates needed
to update system to 10.1-RELEASE-p12."

2. cp -r /var/db/freebsd-update to a USB drive

3. from the air-gapped machine cp -r the files to /var/db/freebsd-update

4. from the air-gapped machine issue "freebsd-update install".  This
command responded with "no update are available to install, run
'freebsd-update fetch' first"

Man page didn't help help. Google suggested the above steps.  I
perused the source of freebsd-install and I suspect that between the
rollbacks and hashes of local system information, that I cannot just
simply copy /var/db/freebsd-update.

Thank you,

Chris