Blend GA and GAds Data

Hi all, I am working on a website performance dashboard and was already able to display all conversions segmented per page type (custom dimension on hit level), country and channel (consolidated to paid and non-paid). This is all set up and can be blended. The next step is to have the same for all cost data (where I start with Google Ads). Importing this data for the three dimensions is pretty easy and straight forward with the Google Ads connector. Now comes the final step: I need to combine both and calculate a cost per conversion for all combinations of the three dimensions. With some Google spreadsheet magic I was able to blend page type conversions and costs, but that's it and it's high maintenance work. I am looking for a way to blend the cost data from Google Ads with Conversion data from Google Analytics to calculate a new metric in Google Data Studio (or Google Analytics), but what I read today this is not possible as Google does not allow to combine country metrics and ad costs or any report from Google Ads with Analytics conversions (not imported). I am very thankful for every hint or solution. :) Best regards, Manuel