You can do this in Mendix, but not by filtering. If you do not want to commit your SearchParameter, you could solve it as follows:
Hi Daniel,
I have struggled with this problem myself. The core of the issue is that there is no IN operator in XPath queries. Make sure to upvote this idea https://forum.mendix.com/link/ideas/580
That being said, you have several options: Rene recommends using filter or java in his answer https://forum.mendix.com/link/questions/88582
Another option that I have used with success is to make the search parameter persistent and commit it to the DB before searching.
Then you could query all restaurants that share a category with the search parameter easily using XPath
[Rest_Category/Category/Category_Search=$SearchParameter]
Hope this helps,
-Andrej