Just when I was getting used to Fedora Linux and the workflow I had with i3/vim/tmux, I joined Facebook, where the only choice I have for OS is OSX, and much of the workflow is tied to a custom VSCode build. With a little bit of work, though, I've been able to mostly replicate the things I liked about that setup.
Amethyst has been a wonderful replacement for i3. Though not as powerful, it does everything I want as a tiling window manager out of the box. Support for spaces isn't as good as I would like, but the tiling and focus switching works quite well.
To replace i3 starting applications and assigning them to the correct workspaces, Hammerspoon has been a nice replacement. You can use it to do window management as it is quite powerful, but it's not as polished as Amethyst.
I've gone back to using the VSCode Vim plugin, but setup hotkeys similar to my nvim dotfiles for switching tabs, opening files, and making splits. Took a little bit of getting used to, and I still like nvim a bit more, but it's a fine replacement.
While I had been using nvim combined with Dropbox for synced notes, I switched to Obsidian for taking notes, due to the amazing internal linking ability. Onboarding at Facebook has required me to take in a torrent of information, and being able to organize it linked markdown files has been a godsend. The hotkeys are not perfect, but it has Vim mode and the developers seem to be quickly adding features that power users want.