This could be improved a lot IMHO.

NXP's IMX6/8 family is dominant in the market, really should have presence there.

And TI's ARM series, still popular in beagleboard family and used widely in the field.

And Intel's N100/N150, though I'm unsure if they're still "SBC" boards.

Allwinner, ESP32 are also major players from China.

Now apparently Qualcomm is entering the fight with new chips on Arduino UNO Q.

NXP and TI are both open source friendly, unlike broadcom. My first choice will be NXP.

Never heard about CIX.