Tamiya has both the Semovente sp gun and M/13 tank tooled from around 1975, and in 2008 reboxed them with some new decals, figures and small PE fret. I know Italeri released these exact same two subjects in the mid 70's as well, but can't recall how they compared. Any other Italian vehicle from WW2 that is in a Tamiya box, is likely original tooling from Italeri. You can check Scalemates to see the origins:
https://www.scalemates.com/
Just looking up Fiat in the above database link, there is a lot of kits to choose from. Purely from a tank perspective, the Bronco tankette series is probably the most modern tooled in terms of injected plastic, along with Italeri's L6 series. The best kits are going to tend to be the resin kind from makers such as Brach Models and Model Victoria, but those fetch much higher prices.
regards,
Jack