Land prices in Portugal (away from the coast and from bigger cities) are pretty cheap for western European standards. It's getting noticed though - a quick YouTube search will show you plenty of examples of expats jumping on the opportunity.
IMO making a profit would be the hard part - the internal market is small and in general produce prices are low.
They do have a lot of advantages: a flat country, good infrastructure for cycling, cool climate. That means you don't sweat on the way to work so you don't need showers and to change clothes.
This actually happens in Portugal. When filling your taxes you can select a non-profit to receive a cut (don't remember how much though). Family and most friends live there, and never have I heard about this changing in any way how they feel about taxes.
construction comes to mind, equipment, materials, things usually sold only to companies. that would be interesting...a small crane shipped to your cottage.
[0] https://youtube.com/@MentourPilot