Since you're using small scale in your example, let's consider what I'd call a micro passive product.
I often find small pockets of time where I can't go anywhere or do anything per se. I have young kids so think house arrest. Right now, mendala coloring books are a thing. Anyone with Adobe Photoshop or Adobe Illustrator can eat up a little of that time while binge watching some Netflix show. Draw some mendala coloring pages. Sell them as digital downloads on Etsy or Ebay. They only make about $.75 each (listed for 99 cents), but the sales trickle in. Depending on your skill, you could rack up quite a few designs - say 500 or so - and your trickle would be pretty impressive.
Mendala pages are just an example. Just a little trolling on etsy and ebay will show you how many different digital download items there are out there and nothing at all from stopping you from joining the group.
Now, this may appear as up front investment and inarguably it is. But not quite like publishing a book. We're talking an hour or two if you're skilled for each unit. Each unit immediately goes up for sale, and only comes down when you say so. You build small blocks of your trickling income a couple hours at a time on your own schedule and just keep piling on so long as you feel it is worth your time.
If you can't draw, then there are many other solutions that are digital downloads. You just have to put some effort in finding what works for you.
Geographical location is irrelevant to digital downloads so your being in Italy will not affect the viability of the plan or product.
This is no different than any other financial strategy - this should not be your entire plan. Times change, and so will the hot download items. Diversify, use the profits form this to build up other investments, etc. Nothing wrong with property so long as you heed the warnings from others. My family has rentals, they are often unoccupied and destroyed by the tenants. They make a decent amount monthly, but when they dont, they cost a decent amount. A good property management company can alleviate you from the headache, as well as a chunk of the profits.
Think SMALL - very small. Make your profits in change and always assume anything over even a modest 5% is probably risking more than you want from a passive source. Physical, non-passive investment has paid hundreds or thousands of percent for me and require little more work than the passive method. Often, it is just a matter of saying - what do I want, and why can't I provide that for others.
Good luck. I'd be interested in hearing how this pans out for you.