"If by equivalent, you mean the fov is the same, ..." — Yes, that's what I meant. I left out "fov" because that is usually understood. At least that's what people usually understood before the idea arose that "equivalence" means DoF at widest aperture exclusively. Now if someone leaves out "fov", someone else is quick to say ERROR!
The latest version of this idea is that all m43 manufacturers are misrepresenting the widest apertures of their lenses. It has now become "dishonest", according to some, to label an f/2.8 m43 zoom as f/2.8 when its DoF equivalent is f/5.6. According to this idea, all f/2.8 m43 zooms should be "honestly" labeled as f/5.6 because aperture describes DoF equivalence only — which it didn't throughout 175 years of photography, ... but never mind that. It seems no one remembers when a light meter's reading of f/2.8 meant f/2.8 regardless of how big the film or sensor was.
If you disregard common usage in photography, lenses across formats are never "equivalent". Lenses can never be equal in value, amount, function, meaning, etc. because there are too many values, amounts, functions, meanings, etc. to consider. Equivalence in one detail is accompanied by non-equivalence in another.
Of course a 75/1.8 in m43 is "equivalent" to a (nonexistent) 150/3.6 in FF if we are only concerned about DoF at widest aperture.
And of course a 75/1.8 in m43 is not "equivalent" to a 150/3.6 in FF because, among other things, a 75/1.8 exists for a current system, is really compact thanks to the small format, and it goes to f/1.8 if desired.
If that was all you meant then, as I said, the vastly cheaper and smaller 70-200 f4 is, using your words "the closest ff equivalent", not the 200 f2, the zoom lens allows you to take exactly the same image across formats. You didn't say the 200 f2.8 either, another vastly smaller and cheaper option, or any one of the 70-300 f4 - 5.6's, which give a very close equivalent image.
The only person being dishonest is you. Manufacturers call a 75mm f1.8, a 75mm f1.8, because it is a 75mm f1.8, you are the one that introduced the phrase "the closest ff equivalent", they do often then say 150mm equivalent and in that instance they really should say 150mm f3.6 equivalent. The understanding of equivalence when referred to different camera systems, hence lenses, is what is needed to achieve the same image, that includes the same fov, dof, noise and shutter speed, a change that doesn't take all into account is NOT equivalent. You erroneously included f2 in your ff equivalent examples, I don't know why, but it was misleading and I simply tried to address that. People reading your initial comment could conclude that if they wanted a Canon 200mm f2 they could buy an Olympus and a 75 f1.8 and get the same images, they couldn't, why am I so wrong to point that out?
As for your "it goes to f1.8 if desired", well again, you are either being dishonest or obtuse, my amp dial goes to 11 and has a Dobly button
. You are propagating misleading information by using the term equivalent to people who don't know better, even though you say you do, well done. My '87 Jimmy has four doors, it is equivalent to a Rolls Royce Phantom.
As a picture is, said to be, worth a thousand words, here are three I did a few years ago for a talk on camera sensors, even when enlarged and printed these images are indistinguishable.