Hello RKK,
I've used a
Plugable USB3-3900DHE on my Oneplus 3T on Oreo with a Dell P2414H display.
The Dell monitor is synchronised at 1920 x 1080 at 60 Hz.
For media, I used a rather old .avi file encoded almost a decade ago.
When using VLC for video, the application seems to recognise our solution as, instead of displaying on both screens, VLC shows an icon on the native display and the video on the external display.
No video pause, no video tearing. To me, it plays smoothly like on the mobile phone.
I also tried the picture-in-picture (PIP) feature you have on Oreo, and it works too (it is a real duplicate here, and full screen duplicate when exiting PIP)
In that case, performance is spotless too, but that's an easier job as the video is smaller.
I'll try at home on my TV later, to make sure the sound matches the image!
Kind regards,
Alban