If you're using fzf.vim (https://github.com/junegunn/fzf.vim) then you can use :Rg or :Ag. This will run ripgrep or silver-searcher and present the results in a fuzzy finder window.
I also use vim-grepper (mapped to leader-g) for finding in files and populating the quickfix list.
Does that work for you? I thought that's what a fuzzy finder is
If I wanted all occurrences of lines that match a pattern I'd use vim-grepper (which uses Ag or ripgrep under the hood) and search with a regex.
If you're using Telescope you can use your fuzzy search to find the lines you want then use <C-q> to send them to your quickfix list.