Can I somehow ask Google to show all places in with rating higher than 4,7 in Belgium?
In the user interface, it only seems possible to filter ratings higher than 4.5 (4.0, 3.5, ...):
In Chrome on computer:
On Android mobile in the Google Maps app:
I was looking in the URL to see if the rating is there so it could be modified easily, but doesn't seem so. To filter rating higher than 4.7, you would probably need to hack more (maybe program something with the API etc.)
You can see something about the history on this page, and it seems to confirm that filtering 4.7 isn't possible in the UI:
When the review filters first came out, they were in whole numbers – 4.0, 3.0, etc. In May 2017, Google introduced half-star increments.