Train Travel Safety

Although the ticket is considerably more, a seat in the Executive compartment on Trenitalia is about the only 100% way you can be sure your bags can been seen, as there are only a few seats in the area and the bag can sit right next to you on the floor. Even if you book a seat next to the luggage racks at each end of first class cabins, you pretty much have to get on before other passengers hog the space with their bags. If you are strong, you can heave your bag in the rack above your seat. I travel with a suitcase and use a thin security chain looped through my travelling companion’s case, which makes it difficult for thieves to pinch. I also have chained my overnight bag to the rack above the seat. There will be much criticism of my suggestions as selfish etc, but protecting my property is my priority.

I always lock my bag and I have also used a small bike chain which I used to secure my bag to the rack (I think I had to use the side metal bar). It was a 5 hour train ride in South America.
If you use a chain, allow yourself time to remove it before arrival at your station.
I recently purchased an airTag for my carry-on roller and will test it out next month. I want to see how the alert system functions on my iPhone when the bag is not close to me, and when I'm using eSIM in a different country.

Years ago, my sister and her family had bags stolen from the sleeping compartment they were in. There are no guarantees.

A cable lock like the one below, is the best solution:

S SYDIEN Cable Lock Double Loops:
https://www.amazon.com/dp/B0BZYBCSN2?ref=ppx_pop_mob_ap_share

also seek guidance from the Man in Seat 61