Although the file explorer you link there was abandoned, a vim-telescope style explorer was merged earlier this year.

However, when you already have a fuzzy-search based file picker built in, an explorer doesn't bring much extra utility.

Totally disagree. I find having both extremely useful. Once I start to get to know a code base jumping through files with telescope is super useful. But when I'm getting spun up on a project and don't know what files I'm looking for, a file tree is super nice.