How can I modify my Keyboard layout or make my own?

I'm on Arch Linux with KDE Plasma 6.6 on Wayland btw.

So here is my problem: I mostly type in German and therefore I need the German keyboard layout since I require the Umlaut-keys

Problem is: The German keyboard layout has a shit position for the "Slash" character ( / )

On the German keyboard layout, You need to press SHIFT+7 on the Keyboard to get a slash character... Which is horrible and idk which idiot thought that is a good placement for the character.

On Linux, I need the Slash character all the time when typing filepaths in terminal. And every "/" that I need to place down slows down my typing insanely because of the trash position of that character.

So I want the right control (CTRL) key to act as another "/" key since I never use right-CTRL anyways and I don't mind it being gone.

But idk how to really set that up, I couldn't find anything in KDE Plasma and I never found good info how to get it in other ways.

Thanks for the help!