The 'coupling' between FoV and DoF changes for every format. Getting just the
right amount of background blur* as well as the right perspective depends a lot on what a particular format offers in focus zone control.
As the FoV gets wider, a larger format enables more focus zone control: the ability to make the DoF appropriately shallow to net that right amount of blur in the background without it turning to total mush. Narrower FoVs work better on smaller formats because on larger formats you can't grow the focus zone enough without stopping down the lens so far that exposure times become too long and problematic. Et cetera. So there is no such thing as "true equivalence" .. there are only approximations. Every focal length/format pairing nets a FoV and a range of DoF possibilities that you have to learn how to exploit for their good qualities and how to workaround for their limitations.
For example, I have been particularly obsessed with the look of images made with the Hasselblad SWC and its Zeiss Biogon 38mm f/4.5 lens on 6x6 film. Calculating the FoV for different formats with different focal length lenses has netted a range of interesting equivalents camera (format) and lens possibilities, and I've tried them all. In testing and experimenting, there's getting the FoV right (which includes the square framing), there's getting the DoF right (which involves figuring out what f/number nets the same focus zone as the SWC), and then there's getting the actual rendering qualities of the specific lens being used to be a close match to the Biogon 38. I've found several pairings that work well and provide a close equivalence (or simulation) of lens qualities and FoV, but with smaller formats (FourThirds, APS-C, and FF) I can't get the same amount of subtle background blur (DoF) at useable aperture settings. This is one of the reasons why I'm moving up to medium format digital for my ultra wide work: 33x44 format sensors cropped square will net focus zone control only a stop and some down from 6x6, not the two to five stops for FF, APS-C, and FourThirds. It will never be exactly the same, but I think it will finally be that satisfying equivalence I've been looking for. I'll know in a couple of months.
I fully support Dave and Matt's notions: Fit the lens that is closest to the FoV you want on your chosen camera and go experiment, see what you can get out of it. For instance, my Summilux 35mm f/1.4 v2 on a FF format M or SL produces one range of FoV-DoF couplings, and with my APS-C CL body, a different range ... depending on focus distance and aperture. Both are great when used appropriately for a particular subject I'm working on—the only way to know when to use what is to experiment enough to know what works for what I want to get.
G
* Bokeh isn't "the amount of background blur." Bokeh is the quality of the blur and applies to any amount of blur. I see the word bokeh used incorrectly like this all the time, but it's best to think of it more precisely if you want to be able to understand and control your imaging. Bokeh for any given lens varies on the basis of distance setting and aperture setting, and even subject type has an effect on it. Experiment with different settings, distances, and subject types to fully understand what the bokeh of a particular lens will be.