Is the resistivity of all (conducting) alloys more than that of all (conducting) metals?

Lead is an elemental metal. Its resistivity is about $1.9times10^{-7} Omega m$.

${rm Sn_{96.5} Ag_3 Cu_{0.5}}$ is a commonly used solder alloy (usually called "SAC305" when used as a solder), and its resistivity is about $1.3times10^{-7} Omega m$. (source)

So there's one example of an alloyed metal and an elemental metal with higher resistivity.

If you meant to ask, do all metallic alloys have higher resistivity than their component elemental metals, then consider lead ($rho=1.9times10^{-7} Omega m$) and ${rm Sn_{63}Pb_{37}}$ with resistivity of about $1.45times10^{-7} Omega m$.