That Lenovo tablet with HDMI input is official, and it's a monster media machine
Amazon.com : Dragon Touch Notepad K10 Tablet with 32 GB Storage, 10 inch Android Tablet, Quad Core Processor, IPS HD Display, 8MP Camera, GPS, FM, 2.4Ghz & 5G WiFi with Micro HDMI
Top Tablets with HDMI Output and Input
Lenovo Yoga X tablet teased, doubles as a portable monitor using a built-in HDMI port - NotebookCheck.net News
Targus Single Video HDMI Dock for Tablet Cradle Workstation – Targus Europe
Venturer Elite2 11.6" HD Quad Core Laptop Tablet PC 2GB RAM 32GB Windows 10 HDMI | eBay
XTRONS Dual Android 11 Car TV Headrest Monitor Tablet for Back Seat with 2 Bluetooth Headphones, 11.6 Inch Touch Screen Portable Video Player for Car, Support Mirror Link, Netflix/YouTube, WiFi, HDMI - Newegg.com
Toshiba Thrive Tablet Review - Walt Mossberg - Personal Technology - AllThingsD
Lenovo Yoga Tab 13 is an Android tablet with HDMI input (Use it as a portable display) - Liliputing
How to Connect an Android Phone or Tablet to a TV
Amazon.com : Fusion5 10" Windows 11 Pro FWIN232 Plus S1 Ultra Slim Windows Tablet PC - (4GB RAM, USB 3.0, Micro HDMI, Intel Quad-Core CPU, IPS HD Display, 5MP and 2MP Cameras,
Amazon.com: BoxWave Cable Compatible with TCL TAB 8 Wi-Fi Android Tablet (8 in) - SmartDisplay Cable - USB Type-C to HDMI (6 ft), USB C/HDMI Cable - Jet Black : Electronics