While Google will not start any overly obnoxious ad-serving, who tells you they will not upload all or a bit more stealthily some pictures for some AI user profiling thingie? Cannot happen? They collected WiFi access points when doing Streetview back when their motto was "Don't be evil".
Sometimes it decides that I'm actually searching for pictures of QR codes and gives me Google Search results for similar pictures of QR codes, which is kind of useless.
As for the second part, that's your personal risk tolerance so I'm going to leave that to you. Google is generally a high-trust brand in America, so most people will find the risk tolerable. If you don't find it tolerable, you shouldn't use it.
While Google will not start any overly obnoxious ad-serving, who tells you they will not upload all or a bit more stealthily some pictures for some AI user profiling thingie? Cannot happen? They collected WiFi access points when doing Streetview back when their motto was "Don't be evil".