quelpa VS live-completions

check out quelpa, it makes it easy.

There is another alternative if you want to install package that's not on MELPA or ELPA, it's https://github.com/quelpa/quelpa. It's using package.el so fully compatible with your current 200 packages, just only use it for package you want. Not only that, it supports to install packages from multiple SVC, not only git like straight.el

or with quelpa:

I don't use icomplete nor vertico most of the time, but I am very familiar with them. I've tried lots of completion UIs: default completion, ido (with ido-completing-read to get it everywhere), icomplete, vertico, selectrum, helm, ivy; and I've written several myself: icomplete-vertical, live-completions, grille, embark-collections-completions.

I too am guilty of once writing a package that updates the *Completions* buffer as you type: live-completions. My package didn't have a way to move the "currently selected" completion from the minibuffer (because I didn't mind switching to the completions buffer for that). Recently u/protesilaos also wrote his own version, in prot-minibuffer.el. I'm sure there are many other examples.