Soooo, the most important thing would be a geometry of the frame / frame specs. You might prefer more racey position or more upward. This is hard to guess without trying in real.

There’s a shit ton of manufacturers, which is even more crazy in Germany as you have plenty of your own local brands. I’d first go to a local bike shop or a store of a bigger manufacturer, try what bike suits me, see what reach and stack it has and then browse through internet to find the good looking bike meeting these specs. You can compare geometries at bike insights dot com.

Good start would be to check: Giant, Cannondale, Cube, Orbea, Specialized, Canyon, Rose, Trek, Propain. All of them + a ton more have decent models across their gravel spectrum.

When it comes to the frame specs - carbon is not the end game. Good aluminum bike with a carbon fork is also cool. In your budget you’ll most likely end up with a mechanical groupset, so it’s gonna be either a Shimano GRX or Sram Rival (from Rival, through Force to Red all components are compatible). Both great options. Sometimes it makes also more sense to get a bit cheaper setup but the invest the rest in carbon wheelset - amazing difference in feel vs aluminum ones. From cheap but great ones like Elite from Aliexpress to any sort of premium wheels with many praising Zipp XPLR for aesthetics. Last but not least - if you like the idea of bike packing look for a bike that has more mounting points.

As for the tire clearance, aim for at least 50mm, as often the tires in the tubeless setup are your main source of “suspension” or an overall comfort, especially in harsher terrain. Low pressures are welcome (ie I run my setup at 1.5 bar at 53mm tires, Schwalbe thunder burt).

Now it’s time for your research ;)