This idea pops ups regularly in guitar forums, specifically ones for DIY effects pedals. The premise is that when clipping/overdriven, it is said valve amps produce even harmonics (as well as odd), where-as solid state distortion/overdrive is mostly odd harmonics, and this brings up the valves vs solid state debate for which people automatically assume valve = good, solidstate = bad, and makes for anice simple argument 'well, odd must be bad, and even must be good somehow!'.
Plenty of beloved guitar tones over the decades used combinations of both types of clipping. I don't believe there is anything inherently magical about even harmonics, although I oft see the repeated statement 'humans prefer even harmonic distortion to odd', which I suspect is entirely subjective. There is so much woo about it all that whilst much of it is based on fact, what exactly these things mean in terms of 'guitar tone' is anybody's guess.
You mention 'like a classic fuzz pedal', which I assume you mean the old fuzz face and clones, which used germanium transistors, didn't have much gain but were rather pleasant sounding and softer than modern fuzzes (mostly because of its low gain rather than the transistors).
Rather than start with DSP trying to boost specific harmonics, if your goal is to try and hear (and see) the difference such harmonic content can make to guitar 'tone', I would build several different clipping stages/amplifiers/fuzz boxes. Play a recorded guitar through them and record the output, then run an FFT on the input and output to see the difference in frequencies. I very much doubt you will find a specific harmonic boost that sounds 'awesome'.