Android is not FOSS.
The Android Open Source Project (AOSP) is, but that excludes all the closed Google apps upon which more and more Android apps rely on.
Almost every smartphone ships with Android, not AOSP, therefor there really isn't a FOSS smartphone market.
Not to mention the million hooks Google's apps put into Chrome search, browsing history, etc. If you use the Google Search launcher to open an app, it sends which app and the time it was opened to Google!
I'm disappointed that the death of Firefox OS and Ubuntu phone leaves us with little choice for FOSS smartphones.