Can you scp a device file

It is not exactly "pipe", but you can basically tell scp to copy specific FD (which can be pipe) from your host to the other. Simple bash command like this:

(scp does not work as it needs a size in advance):

scp <(tar cz files to compress) host:/path/to/new.file

but it can work with pure ssh:

tar cz files to compress | ssh host "cat > /path/to/new.file"

Those are simply (special) files. They only serve as "pointers" to the actual device. (i.e. the driver module inside the kernel.)

If some command/service already opened that file, it already has a handle to the device and will continue working.

If some command/service tries to open a new connection, it will try to access that file and fail because of "file not found".

Usually those files are populated by udev, which automatically creates them at system startup and on special events like plugging in a USB device, but you could also manually create those using mknod.