IMO tmux + a scriptable terminal editor (Vim, Neovim, Emacs, etc) turns Unix into a very nice IDE — but it's pretty dependent on becoming deeply familiar with those two tools: a multiplexer and an editor.

I wouldn't say Unix is an IDE, really; but you can build a very nice IDE for yourself using Unix tools, as long as you have a sufficiently configurable terminal multiplexer and a sufficiently configurable terminal editor.

One pretty major difference between "Unix is an IDE" vs "you can build an IDE around Unix" is that, well, the terminal editor is actually pretty close to an IDE — you can have language server based autocomplete, refactoring, linting; UI for git; etc. So, it's not really that Unix is your IDE; your editor is. But the nice thing about running it in a multiplexer in a terminal, though, is you have instant and easy access to just about any other command-line tool just a keyboard shortcut away, and it can be organized visually wherever you like — a pane on the side, beneath, zoomed in temporarily to encompass the screen, hidden in a tab, etc.

(Sufficiently advanced terminal emulators could also fill in for tmux here.)

I think you get many of the same benefits using a tiling window manager... But well, the best ones require running Linux (or one of the OSS BSDs); the options for your company-provided Macbook are fewer and less good. Tmux + terminal editor is pretty nice as something that works in any Unix environment.