Is the Microsoft Surface Laptop suitable for image editing with Photoshop?
The only disadvantage should actually only be the small screen size, right? Do I have to be careful where else?
You should be careful not to get a Surface Pro X, which has an ARM processor. Photoshop is optimized for 64-bit Intel processors. There's already an ARM version, but it is currently only running moderately. So it could take a while before Adobe delivers a version that runs relatively well.
But I would do without the Pro X because there isn't a lot of software that runs on ARM processors. So if you ever want to install camera software or graphics tablet drivers, there are sure to be problems.
In principle, Photoshop should run fine on the Surface Laptop. But, as is so often the case, it all depends.
If you are just starting out with Photoshop and are not doing any particularly clever projects, the performance is actually easily enough. If it is not a problem for you financially, it should be 16 GB of RAM.