Using a content picker within a content app

I need to create some content apps, to perform actions on the content.
I can create some forms easily and consume them. But I don’t find any example or documentation on how to use a content picker. up to v13, it was so easy using umb-property-editor.

Hi,
Try poking around in here Polls-17-Test/UmbPollsClient/Client/src at main · huwred/Polls-17-Test

I use a custom picker for selecting Polls