Emacs is a gui editor. It has a shell mode, but it's primarily supposed to be used through the GUI. GUI Emacs is literally everything you described looking for above - an advanced GUI with more features than you could evere learn, yet one that still retains first class focus on keyboard UX.
Sorry for the late reply. I'm actually a huge fan of modal editing as well, can't live without it, so I use evil - and it's perfect. GUI emacs does everything that any other IDE does, and that's what I like so much about it. With vim or any of it's GUIs, normal IDE features feel like "duct tape" on top of the program. Whereas, emacs was meant to be used in this context. I mean, for example, when programming in C I can even use emacs to debug (it has a GUI for gdb). And those kind of advanced IDE features are available for any language. Not even touching the fact it's just a lisp machine and you can build any kind of program you want in it, it takes extensibility to the next level with a lisp dialect that's relatively easy to learn, whereas extensibility in vim is limited to googling for vimscript code someone else wrote (unless you take the time to learn vimscript shudders). Emacs gave me everything you said you were looking for, at a time when I was looking for those exact things. I wanted a modal editor like vim that actually was an IDE, had IDE features, and was completely extensible. Emacs checks all of those boxes.
If you're a vimmer and want to start out with emacs, try spacemacs. I used it for a year before building my own emacs config. It's an incredible program, won't take you long to get running if you're used to vim, and after a week I'd bet you'll have a hard time going back to gVim.
