The original 60's fuzz pedals (notably the Gibson Fuzz-Tone and the Arbiter Fuzz-Face) used Germanium transistors, and modern builds of those classic circuits still do. Silicon simply does not behave or sound right in those simple circuits. I have a Fuzz-Face that is the best distort pedal I've owned in 60 years of guitar playing. Three Ge transistors, maybe a half-dozen passive components. Simple and beautiful.
More complex circuits benefit from silicon because they typically work with boosted signals, or they're using IC op-amps instead of discrete transistors. But you pay a price in increased noise and diminished clarity.
There's one big problem with Ge-based pedals, though. They misbehave when they get hot, whether in the studio or onstage. The transistors' bias changes as the leakage currents drift, and the pedal gets choppy and can stop working altogether (e.g. read the history of Hendrix and the Fuzz-Face). I learned when playing outdoors to shield my pedal from direct sunlight. But if you manage the temperature, Ge pedals are the best.
Ge transistors will never disappear as long as guitarists are around!
You are absolutely right about temperature problems with GE transistors. I had an old portable record player I used to take to record shows to sample the wares. If it sat too long in a hot car, the output dropped to near zero.
A while back, I repaired a vintage germanium-based Japanese fuzz box which had a bad power switch and some wiring problems.
I could never figure out how the thing worked, but what it did was introduce a spike into the waveform (it was not a simple clipper). When fed with a sine wave, the spike only appeared on the downward slope, about 1/3 down from the peak. The eventual buyer described the sound as “fabulous”.
Guitar people are actively seeking out vintage germanium transistors for new fuzz-face builds, and are paying good money for them.