using a garmin gps in france/italy

https://buy.garmin.com/en-US/US/maps/on-the-road-maps/europe/c452-c454-atFILTER_REGION_EUROPE_01-p1.html

Yes I do have experience with this.
1. You need to buy the SD Micro card with European maps.
2. You can buy those directly from Garmin at a higher price, or you can buy them on Amazon for much less (which is what I did). I see them at $60 on Amazon (vs $100 at Garmin) but maybe if you search you can find a deal at even less (I paid $30 two years ago on Amazon for brand new maps card for "City navigator Europe NT).
3. Once you receive the SD microcard you purchased online, to learn how to install them, Google: "how to install European maps on Garmin 2405 series". There will be a plethora of U-Tube video demonstrations on line. Just watch the video and follow the instructions. It's actually very easy.

I had one that came with Europe maps in it(Nuvi 370). It worked very well in France, it even let us know where the speed cameras were.
A note on adding maps to an existing gps unit, check the Garmin website(or call them) to make sure your model can take the added maps and that it has enough room on it. I have a Nuvi 265 that would have taken an SD card for Europe maps, I did one US map update on it now that card can't be removed or the unit is useless:(

Our last trip in Sept we ended up using our daughter's French phone's (iPhone) gps to get around. Wouldn't want to be without some sort of gps now. We would have had a tough time getting around the countryside without it and just the map.
I ended up buying a 2577T recently with US and Europe because my old 370 is lost and we won't always have access to our daughter's phone.

Although Europe seems to call for a premium price, you might also look around for a europe-only GPS with lifetime map updates. I have found that even Garmin GPS units have a limited lifespan - memory size issues, vibration in the car, battery deterioration - and you might want to have a newer unit just for that job. On the other side, if you don't plug it in except one month a year, the battery life may suffer anyway, due to complete discharge when in a drawer.

To be more specific, most Garmins I've had have eventually received map updates that were too big for the internal memory. And when I added an outboard memory card, speed of screen-painting and Recalculation suffered. I'm still a Garmin buyer, but you should go into this with your eyes open.

Or you could rent your car through AutoEurope. Right now they are offering free GPSs with rentals in western Europe. Then you don't have to worry about whether your GPS will work, etc. You would have to pay the round trip shipping costs of around $40.

Another note....I always carry a map and print outs of where we are going, if I know ahead of time, as a 'just in case' the gps konks out.

If you buy a GPS rather than update yours (I've also heard of memory issues updating with Europe maps, but that may not affect you), I'd suggest a TomTom over Garmin. I've used both for more than a couple of years each. Right now I have a Garmin and am considering purchasing a TomTom (with both US and Europe maps) for the next trip.

Last trip the Garmin started me going north when I wanted to go south (which was probably me inputting the destination wrong, one letter can change everything) but also wanted me to go the wrong way down a one way street and refused to calculate another option (kept taking me back to the same one way street, yes it was freshly updated). At one point it navigated to the same street address twice but went to two completely different parts of town; as far as I could tell, neither was right.

I feel the TomTom navigates better, with more reliable arrival times than Garmin. I also like to check a route for tolls vs. no-tolls. In a Garmin, it's a system setting. You have to go into system tools to test a toll vs. no-toll route. TomTom asks if you want to avoid tolls for each route calculation. It's much easier to try both ways and decide whether paying a toll saves significant time or not.