Web browsing - Parental Controls on Apple Watch

We bought our 10 Y/O son an Apple Watch to keep him safe by knowing his location and being able to communicate with him. Unfortunately, someone sent him a text with links to **** images/videos, and when he clicked on them (not knowing what they were) a web browser opened and displayed the images/videos with no filter. After he showed me this, I looked for a browser on the watch and there isn't one to disable. I also discovered that you can say "hey Siri, show me pictures of xxx." and again a browser pulls up images of whatever you are searching for. We immediately took his watch away until we can find a solution to block web browsing or set up parental controls on the Apple Watch. So far I have not been able to find a way to do this on the Apple watch. This seems like a huge liability for Apple. Please help!