I don’t know what your idea of “lower impedance” but a pure tube stage has an input impedance that measures close to open. Off the range of my multimeter, I bet. You just see the Miller capacitance and with the grid-plate somewhere around 1.6pF and maybe 20dB gain, it’s not a lot. The input impedance of the guitar amp is usually dominated by the 1 MΩ resistor to ground, and the tube barely registers because the input impedance of a preamp tube is so high. This is usually considered “high impedance” (as opposed to “ultra high” like you see in a piezo amp, which might run 10 MΩ).

It is very common to see solid-state equipment with lower input impedances, especially guitar pedals.

There’s a lot of weird voodoo electronics repeated around guitarist’s forums so you got to watch out. Just quick fact check: small tubes = high impedance input, in most normal configurations, normal operating conditions (cathode is positive relative to grid).

Just as another point of reference—this is why you hear about “tube microphones”. These microphones have a vacuum tube inside them as a preamp / buffer, and the reason you might want to use a tube for these applications is precisely because the input impedance is so high. When they moved away from tube mics what you see replacing them is something like a FET, possibly bootstrapped, to try and replicate the naturally high impedance of a tube.