Holly,
A hotshoe is a hotshoe, except for some of the older Nikon F - F3 models, which were located over the film rewind crank.
What's wrong with the Metz?
That would be my first suggestion if you were asking for a recommendation for a flash for your RZ.
You can mount a Canon, Nikon (non F), or any flash with a standard shoe. You will have the choice of full manual or "Auto" operation (sensor on flash), but will not have any TTL functions.
Because you were using the Metz with sync cord (no TTL) with "No worries," you should have no difficulties.