Do you know if it is somehow possible to apply Segmentations to Segmentations when using dynamic content?
E.g. if I'm making an email dynamic based on country, to have a further segmentation that says, if country is Italy, AND job title in CEO display x content, if country is Italy AND job title is Manager, display this other content.
No it's not. You will have to create a unique segmentation that mixes all you criteria.
You can do multiple-segment matrixes with Velocity, which is a powerful form of dynamic content, even if not Dynamic Content™.
If it's something you'll reference other places (SFDC, RCE, etc) you could also create a field for the segment (e.g. Industry Segment where the value is populated by the name of the segmentation), and create a campaign that populates the field based on segment membership.
You can also reference static lists in segment smart lists, so you could set up a campaign that adds people to lists depending on what segmentation they are in, and reference those lists in other segments.