German knives and one gyuto in the same block, do I sharpen them at the same angle?

It matters and you have diagnosed it correctly. The conventional figures are roughly twenty degrees per side for Western knives and around fifteen for Japanese ones, and the reason is steel hardness. Harder Japanese steel supports a thinner edge without folding, and that thinner edge is why the knife felt so good out of the box. Putting a twenty degree bevel on it has made it more obtuse than the factory intended, so it feels duller sooner even though it is technically sharp.

Do not do the reverse, though, which is the mistake people make once they learn this. Grinding a fifteen degree edge onto a softer German knife gives you an edge that feels incredible for one dinner and then rolls over the first time it meets a bone or a chopping board. Softer steel needs the extra material behind the edge to support it. Match the angle to the steel, not to the sharpest number you have read about.

I want to argue that consistency beats the number for most home cooks. An edge held at a consistent nineteen degrees will outperform one that wanders between fourteen and twenty two, because the wandering one never actually forms a clean apex, it forms a convex mush. If you are freehand and honest about it, pick one angle you can repeat, use it on everything except your gyuto, and put your effort into holding it rather than into hitting a target you cannot measure. The gyuto is the one exception worth treating specially.

Practical way to hit those angles freehand without buying anything. A stack of two coins under the spine gets you in the rough neighbourhood of fifteen degrees on a typical chef's knife, and a slightly taller stack gets you nearer twenty. Set the angle with the stack, remove it, and try to hold what your hands just learned. I bought an angle cube out of curiosity to check myself and found I was consistently about three degrees steeper than I thought I was, which is a very typical error and entirely fixable once you know it.

Match the factory angle unless you have a specific reason not to. Twenty for the German knives, fifteen for the gyuto, and do not mix them up.

I spent a year sharpening everything at whatever felt right and wondering why my results varied. What fixed it was not learning the correct angle, it was marking the existing bevel with a permanent marker before I started and looking at where the marker was coming off. If it is only coming off the shoulder, I am too shallow. Only at the very edge, too steep. That one trick told me more about my own hands than any number did.