The system-wide shortcuts are a bit less discoverable but, they’re there if you know where to look: either search “keyboard shortcuts” in the os help system or go to system preferences > keyboard > shortcuts.
I'm not exactly a Windows fan, but (generally speaking) in a standard windowed program, just hitting alt focuses the menu. Windows is almost entirely navigable by keyboard by default, without a mouse. It's much more discoverable and efficient.... although that's been tanking since Win 95 :)
Also, if I use the Finder help menu to search "keyboard shortcuts", it gives me a local help article "Use macOS keyboard shortcuts". This article talks about a bunch of ways to find keyboard shortcuts and also links to this knowledge base article: https://support.apple.com/en-us/HT201236 (This is actually a sort of step backwards, from when I did exactly this around '07: at that point, the Mac Help system actually listed a bunch of handy keyboard shortcuts and didn't rely on online resources for them).