So I'm very happy with vim, and have been for the past quarter century (I used Elvis before that. Remember Elvis? It was awesome! - But I digress...)
I have to admit though, while I pity the fools in my company who use VSCode and mock me for using vim in the terminal, yet in fact produce code much slower than I do, I envy their IDE that suggests function and variable names in other project files.
So I've been looking for a nice, easy-to-install solution to get some of that goodness in vim. Nothing fancy, just autocomplete suggestions to avoid having to grep names I forgot or having to yank/put text manually to prevent typos. And mostly easy, because for some reason, I'm properly allergic to any sort of vi configuration - be it vim or any other vi flavor.
So I gave Neovim a shot. My plan was to ensure Neovim was at least as good as Vim, then try to install Treesitter. But that plan immediately went south, then kept on being a proper pain in the ass until I finally realized this was going nowhere fast and I didn't want to spend countless hours configuring that awful thing, so I gave up. I wasn't asking for much but Neovim totally failed to deliver.
And then I found the solution I was looking for all along: YouCompleteMe. It's as simple as installing the handy vim-youcompleteme .deb for my distro (Linux Mint), running vam to install it and voila: a working autocompleter that actually works in 3 minutes flat and doesn't get in my way.