I switch back and forth between using autocomplete/LSP in an IDE and plain-jane vim. Autocomplete isn't the end-all-be-all of productivity you're making it out to be.

I've only found it truly useful in a codebase, language, or library I'm unfamiliar with or haven't touched in a long time.

It doesn't do much for me most of the time as I'm usually thinking or walking around the code, but the codebases I'm in usually are extremely easy to jump around in with fzf.

Properly naming functions/classes/modules goes a long way.

Writing the code doesn't generally take a great deal of time once I know what code needs to be written, so there's little value to be gained in optimizing that part of the process. I can think while I type, after all.