Chrome on Android can do Picture in Picture or PiP since version 8.0 Oreo. This is not something new. However, there is a new API that Google has been working to implement across the web so that developers easily integrate PiP and make it work on all browsers.
That is coming to Chrome for Android too.
The stated objective of this API is to: allow websites to create a floating video window always on top of other windows so that users may continue consuming media while they interact with other content sites, or applications on their device.
This API will connect to the existing PiP solution provided by Android, and Chrome will continue to support PiP. (Thanks Šime Vidas for correcting me)
This API includes features like Auto PiP and we will see regular updates since it has a larger reach. I have also seen discussions about supporting PiP for elements beyond videos. We will have to wait and watch what interesting things the developer community comes up with!