The philosophy was that anything visible in a context menu should also be in the app-wide menu bar. Instead of bring up a context menu and click Copy, you would find the Copy menu item in the menu bar. Therefore such menu items can be assigned any keyboard shortcut by the user.

I quote from Apple https://developer.apple.com/design/human-interface-guideline...:

> Always make context menu items available in the main interface, too. […] In macOS, an app’s menu bar menus list all the app’s commands, including those in various context menus.

Therefore one can rightly conclude that there is no need for a key to bring up a context menu.

> There's no option to bring up a context menu with the keyboard.

That used to be the case but has changed. Since at least macOS 15 the context menu key on typical keyboards is recognized and functions, and on other keyboards it can be opened with Ctrl+Return.