Altas with different numbers of page and maps for every feature

Question

I want to create an atlas and the features to show are OUTSIDE the feature of the layer coverage.

The atlas feature 1 is Switzerland, but I want to show all embassy that are geographically OUTSIDE Switzerland, but that belongs to Switzerland, namely the Swiss embassy around the world. To show them I will create many maps and manually define the maps views. The same thing I will 2 with atlas feature 2 that is France and so on. To show them I need to create many different maps and pages for every atlas feature because every country (namely atlas feature) has different numbers of embassy and so on.

Switzeraland has x embassy around the world, French has y embassy and so on. So every atlas feature need different numbers of page or maps shape inside the page. My problem is that I don't know how to create an atlas with different number of pages and map shapes. It seems me that atlas can work only recurrent. If feature 1 has 3 page, feature 2 can have only 3 page, and feature 3 can have only 3 page. How can I have an atlas that change the page number for every atlas feature?

I add an example. You see an atlas with maps shape differents and in feature 1 you see the there are two page, in feature 2 there is 1 page. So, feature 1 has not the same layout of feature 2 (one vs two page and so on)

Someone could ask me, why do yo need an atlas? I need an atlas because it helps me to automatically create a filter of the vector embassy that otherwise would have shown the embassy of the entire world. Feature 1 of the atlas that is Switzerland allows me with the filter in the symbology to see automatically only the Swiss embassy from the vector embassy and feature 2 only from France and so on. Atlas has only this purpose.

Pay attention: I don't work with embassy but I used only as example to show the concept in this thread.

Answer 1

Provided your data has the right attributes, you would need to use a Report to accomplish this in QGIS. An Atlas will have the same exact layout for every feature in the atlas coverage layer, and while you can do a lot with it, it's not as dynamic as it sounds like you need.

You can think of reports almost as nested atlases, though they can be quite a lot more than that. For each feature in one layer, you can have it create a layout for each matching feature in a second layer. (Or a third, or fourth, etc.)

Here are a couple of scratch layers: country polygons and embassy points, each with a country attribute. I've symbolized both layers on said attribute to make this link clearer.

On the menu toolbar, choose File > New Report... Once you have your report window open, add a Field Group Section. With the new section selected, choose the countries layer, and countries field as well.

Create a second field group section below that, this time choosing embassies as the layer, and some identifier field. The report will automatically look for a matching country field in this sub-group layer.

For each field group in the atlas, you can check the box to Include body, being an atlas layout. So you could have a layout for each country, or skip it and go to the embassies directly, depending on what you need. Below is the first page of my report, showing a separate layout for the country itself, then for the first embassy.

If what you're really looking for is a unique layout design for each country/embassy, I'm afraid there's no simple way to generate that. The best you could hope for is perhaps a separate layer for each country, each of which could be its own Field Group in the report.