Recommendations for garage finished floor construction 10-15mm thickness?

In my opinion, that doesn't make any sense, the floor will look sh... later -. Cove molding also makes little sense. I would say, sand, level, clean walls, and later paint or possibly epoxy depending on the budget.. The floor (floor slab) can actually stay as it is for now??

So, bring leveling compound up to the wall?
The floor could stay as it is for now but the doors will then "hang in the air" (about 1.1 cm above the floor) and I want to finish the floor because I don't have a basement and would like to store some things in the garage or set up a shelf/workbench.

What is the "standard solution" for a garage on a floor slab - not tiled -?

I now have two offers. One is the full package with leveling compound and 2x coating as well as cove molding, etc. Costs: 13k gross (specialist company for renovations)! Another offer: leveling compound Remmer Multiplan SIC, edge strip: 5k gross. But here I am still missing paint coating, etc. (craftsman).

This is absolutely crazy! Are we talking about a bus depot here? More likely about 60 m2 max, right? You can apply the leveling compound yourself, it takes 2 hours and a small three-digit amount. You can also use only 2 mm to level and then paint directly after priming with concrete paint (e.g. Albrecht Concrete and Garage Seal, 60 euros is enough for a double garage). Everything right up to the wall, yes.

The floor could stay for now but the door will then "hang in the air" (about 1.1 cm above the floor) and I want to finish the floor because I don’t have a basement and would like to put some things in the garage or set up a shelf/workbench.

To compensate for the one cm, you take a garage door threshold seal, 100 euros Now you have for < 500 euros a level, painted and resistant floor and a tight garage. You can do the walls sometime. And if you like, you can also stick a 3 mm rubber mat all around as a replacement for cove molding. And with the 15k saved you can get yourself a car too ;)