NXP I.MX8M platform - “The SCMI questions aside, I honestly do not think the iMX8 is a very good example to work with. The non-BSA compliant UART and PCIe are especially concerning, but that can be said for most SoCs in this space. Also, there is no good reference UEFI/ACPI EDK2 open-source code for the iMX8. There is code that can be downloaded from NXP that combines the Uboot FW (as a low-level initialization FW) with UEFI implementation from MS Project Mu (using EDK2 components, but not exactly EDK2). The Project Mu components add UEFI, ACPI, and SMBIOS on top of Uboot. However, as far as a I know, that combination lacks several UEFI pieces, which results in limited OS boot at least for now (only boots Windows, not Linux).”
Phytium SoC - “The Phytium SoC-based PC is the best as far as I know. It supports all OSes very nicely with ACPI support. They also have an EC solution in their laptops.”