Not sure if you’ve ever seen a product called Xojo (formerly REALbasic), but I like their style of presenting autocomplete. It’s something I wish all IDEs did.
Instead of just showing the entire list of items, it shows an ellipsis when there’s more than 1 option and if the the user hits tab the list of potential items is shown. If there’s only 1 option, it does the greyed out remaining text thing to the right of your cursor and you can press tab to accept it.