The issue of dropshipping isn't necessarily if you can target 3.5mill people. My country, Norway, is about the same ..
the question is if the target group is highly aware of the opportunities online. IF they are, your niche will be significantly smaller, as many customers will simply know about aliexpress, about google image search and so on ...
but if your target market has purchasing willingness combined with your ability to market your goods in an appealing way - then 3mill target market is more than enough...