How to make an accessible searchable "select" list?

I was reading this article on gregs website: https://www.gwhitworth.com/posts/2019/can-we-please-style-select/
This article points out why we need <selectlist>, but also says that the top frustration with <select> is "Not being able to create a good user experience for searching within the list." There is an example in the demos which adds a text input in the listbox to filter which addresses this top frustration, but based on what I've been hearing from accessibility experts, there should not be any interactive content inside the listbox element except for <option>s.

So my question for accessibility people is: what is the right pattern to create a select-like thing where you can filter the options? Is that just called a combobox, where instead of a button to open the listbox there is a text field?

I see in this combobox in aria practices that the user can still sort of commit any text they want even if its not a valid option... what if you want to limit the possible choices to whats in the listbox like the one in the demos?

@scottaohara