For commuting I would look for a sturdy touring bike, a gravel bike AFAIK is intended for recreation and isn't built around the purposes of someone actually depending on it for transportation. Touring bicycles are not only stronger and built to last, but they're usually built to be easily maintenanced if broken down on the side of the road, etc.

I say this as someone who started commuting with a hybrid bicycle and had endless problems - broken spokes, eventually a broken frame, etc. The recreational bikes are just not as good as touring bikes for commuting.

The touring bikes I've seen typically have thicker tires and enough tread to handle dirt roads and grassy paths.

A used mountain bike from the 1990s would be a perfect way to start without spending much money. They have wide tires, flat handlebars, sturdy frames, and attachment points for a rear luggage rack. The replacement parts are inexpensive, too. I do not know if they are common where you live, though. In the US and Canada they are easy to find at thrift stores and used bike shops.

Go for something with wide tires so you're comfy on the dirt roads. Gravel bikes usually make you bend down pretty far, so they mostly make sense for bikers who put a lot of pressure on the pedals eg. go fast. They often don't come with lights, fenders, stand or rack to save weight. On the plus side, they have very comfortable handlebars (if you put enough pressure on your pedals to counteract your weight). In the end it all depends on your fitness and level of comfort you whish. I use a gravel with 47mm wide tires for a regular 20min commute. I go fast and put a rack on my bike so it's pretty much perfect for me. I can also do light mountainbiking or go on long rides with it. I like that I can use it for all kind of rides.

I personally didn't like my gravel bike/drop bars for commuting or any mildly chunky off-road (maybe it wasn't a good fit for me, but I didn't like being so far forward - poor visibility and uncomfortable, and I wasn't racing). I second larger tires (and ability to run low pressures with them for comfort).

Check out adventure/all-terrain bikes for some of that mixed terrain practical use. An Italian brand makes one that your local shop may stock? https://www.cinelli-milano.com/collections/adventure/products/hobootleg-microshift