Creating a dynamic filter for URL to PowerBI data (from Power Apps Portal)

Dear Power BI Fellows.

I have a serious problem. I cannot seem to create filter to produce a Power BI report dynamically.

I have a report in Power BI that is represented as https://myReportURL/ --> I want to return results only based on a dynamic value (actually, to be precise, the user ID). 

So here's what I have:

https://myReportURL?filter=myTable/myColumnName  eq {{ user.fullname}} " % } 

the result of user.fullname is in fact a result in MyColumn column. 

Its not being accepted. WHy is that?

How on earth do I send this URL a variable? I understand that this variable must be a String, and it is.. The full user name is always a String. 

Its not working at all. I've scoured all Microsoft pages - Microsoft only seem to talk about how to send  static Strings to the URLs. 

I'm really desperate right now.

Thanks for pointers or advice. I'd have thought with Liquid this ought to be a straight forward task.

I've tried even creating a variable and assigning the URL filter a variable - the same : it doesn't work... it only works when I actually specify the string outright i.e. eq 'John Smith' 

Thanks