I skimmed through this thread a couple of times, and here's a quick summary. I am new to this topic, so please correct me if I am wrong.
To run LCNC comfortably, the board must have at least 2Gb RAM (4Gb recommended), 1GHz dual-core ARM CPU and a GPU with a known-to-work driver.
To run stepgen, the board must have a microcontroller or FPGA. The microcontroller core might be a part of SoC design (in this case the communication between Linux and MCU is done through some sort of shared memory), be a separate part on the board (in this case the board should be routed so that SPI lines of SoC and MCU are connected) or be on a different board (connected through SPI, Ethernet, PCIe...)
The most popular board is currently Raspberry Pi 4 Model B. Not because better than others, just because it's noob friendly and the community around it is huge. Remora currently only supports RPi's SPI, but there was at least one attempt to rewrite it to use a more universal driver.
The most popular Chinese SoC manufacturers are: Allwinner, Rockchip and Amlogic. Some Allwinner SoCs have a built-in AR100 core that was successfully used for stepgen. Rockchip SoCs usually have several Cortex-M0 cores and Amlogic SoCs have a Cortex-M4, but so far nobody tried to use them for stepgen.
Some SoCs from more reputable manufacturers are Texas Instruments AMxxxx (they have IT's own design PRUs that were successfully used as stepgen), NXP i.MX8M (they have Cortex-M4 that could be used as stepgen), Renesas RZ/V2L (they have Cortex-M33 that could be used as a stepgen).
Soon, RISC-V based options for both Linux and MCU side should become available.