I am working in a limited space in an old house approximately 24 inches square. I want to cut and reroute a galvanized water line around the perimeter of this space to allow an air duct to pass through. Question: Are there any plumbing galvanized fittings (like the shark fittings for pex or copper) that would hold the pressure and allow me to press them on the line that I have sawed off so I could reroute the pipe?

Is that water or gas pipe ?

The best, and recommended fix is to re-thread the cut ends, reroute with new gal.pipe and reconnect with Left-to-Right nipple and coupling.

Also, if you don't want to thread inside that limited space, you can remove the cut pipe to the nearest fitting and start from that point on.

Then you could use "Quick Connect" coupling for galvanized pipe. We use them for temporarily connecting 2 gal.pipes w/o need of re-threading them. However, we don't trust them and eventually replace them with solid pipe. See the pic...

If it is gas pipe, than you have to go with rigid pipe...