That's a good question.
According to gs.statcounter.com, Linux usage rose from 2.47% in January 2018 to 2.61% in January 2019, so it's low, but rising: http://gs.statcounter.com/os-market-share/desktop/spain/2019
I remember reading about the Autonomous Community of Extremadura creating #GnuLinEx for public schools and institutions (no active links, not a good sign), and Barcelona recently touted its migration to Linux & #FOSS (https://itsfoss.com/barcelona-open-source/), but these are the only cases I'm aware of.