https://github.com/lem-project/lem/ supports CL, Python, C, Rust, CSS, Go, HTML, Java, JS, Nim, OCaml… (see the modes/ directory), it has a directory mode (à la dired) and it seems to support LSP (I only tried it for CL so far). It is very much Emacs inspired, but is lacking documentation and self-documentation features :( There is Lem-OpenGL ! https://github.com/gregcman/lem-opengl
The most functional, feature-complete, proven editor is the LispWorks IDE: http://www.lispworks.com/ A review: https://lisp-journey.gitlab.io/blog/discovering-the-lispwork... It's proprietary. The free version has annoying limitations. It is written with the portable CAPI framework. It has an excellent graphical stepper.
And, you might not know, but popular editors are getting good to very good support for CL now, at last. SLIMA for Atom nearly reaches feature parity with Slime (it doesn't have a stepper). For VSCode, see Alive. There's a Jupyter kernel, an Eclipse plugin and more. https://lispcookbook.github.io/cl-cookbook/editor-support.ht...
libraries: https://github.com/CodyReichert/awesome-cl