Hello! In the release notes for Windows Insider Build 23521 Dev Channel (August 10, 2023) the following was included:
[Search on the Taskbar] Windows Search now uses the Microsoft Bing Search app to return web content and search results. In the European Economic Area (EEA), you can enable installed Microsoft Store apps that implement a web search provider to return web content and search results in Windows Search through Settings.
I haven't been able to find any documentation or other information on how this might be implemented. Can someone point me in the right direction?