Rock Pi 4 Raspberry Pi Compatible RK3399 Board to Sell for $39 and Up
https://www.cnx-software.com/2018/11/08/rock-pi-4-raspberry-pi-rk3399-board/

There will be two variants with Rock Pi 4 Model A and Model B sharing most of the same specifications:

　　SoC　Rockchip RK3399 big.LITTLE hexa-core processor with　
　　　　2x Arm Cortex-A72 @ up to 1.8 GHz,
　　　　4x Cortex-A53 @ up to 1.4 GHz,
　　　　a Mali-T864 GPU with support OpenGL ES1.1/2.0/3.0/3.1, OpenVG1.1, OpenCL, DX11,
　　　　and AFBC, and a VPU with 4K VP9 and 4K 10-bit H265/H264 decoding
　　System Memory　1, 2 or 4GB LPDDR4 @ 3200 Mbps
　　Storage　eMMC module socket, micro SD card slot up to 128GB, M.2 NVME SSD socket
　　Video Output / Display Interface
　　　　HDMI 2.0a up to 4K @ 60 Hz
　　　　2-lane MIPI DSI via FPC connector
　　　　Dual independent display support
　　Audio　Via HDMI and 3.5mm audio jack; HD codec supporting up to 24-bit/96Khz audio
　　Camera　MIPI-CSI2 connector for camera up to 8MP
　　Connectivity
　　　　Rock Pi 4A　Gigabit Ethernet
　　　　Rock Pi 4B　Gigabit Ethernet with PoE support (additional HAT required),
　　　　　　　　　　 802.11ac WiFi 5, Bluetooth 5.0 with on-board antenna
　　USB　1x USB 3.0 host port, 1x USB 3.0 OTG port, 2x USB 2.0 host ports
　　Expansion　40-pin expansion header with 1x UART, 2x SPI bus, 2x I2C bus,　
　　　　　　　　1x PCM/I2S, 1x SPDIF, 1x PWM, 1x ADC, 6x GPIO, and power signals (5V, 3.3V and GND)
　　Misc　RTC
　　Power Supply　Via USB-C port supporting USB PD 2.0 (9V/2A, 12V/2A, 15V/2A, or 20V/2A)
　　　　　　　　　 and Qualcomm Quick Charge 3.0/.0 (9V/2A, 12V/1.5A).
　　　　　　　　　 It’s also possible to power the power via a 5V/3.4A power adapter, but it is not recommended
　　Dimensions　85 x 54 mm