Lenovo Yoga Tab 13 is an Android tablet with HDMI input (Use it as a portable display) - Liliputing
Plugable Active DisplayPort to HDMI Adapter - Connect Any DisplayPort-Enabled PC or Tablet to an HDMI Enabled Monitor, TV or Projector for Ultra-HD Video Streaming (HDMI 2.0 up to 4K 3840x2160 @60Hz) :
Top Tablets with HDMI Output and Input
Apple 7.9" iPad mini (Early 2019, 256GB, Wi-Fi Only, Gold) - Premium Bundle (New-Open Box) - Walmart.com
Top Tablets with HDMI Output and Input
Tablet With Hdmi Output
TCL Shows Paper-Like Nxtpaper Max 10 Tablet at MWC | PCMag