Looking forward to this one.
The SoC and switch are maintained in Linux:
- Linux 88F7040 dev board support
- 7040 dev board in OpenWrt
- Linux 88E6393X switch support binding + driver
The Mikrotik promo video shows board shots which look like there are UART pads (top left) and an SPI-NOR chip (which usually holds the RouterBOOTs, hard & soft configs, and a DTB). The 7.1b6 arm64 firmware has a 70x0*fwf, but device will likely have no-uart set in the hard_config, so no RouterBOOT console without changing that bit on NOR.
Expecting to have to patch Linux to load our DTB from an ELF section, or use an additional bootloader.
I will not be able to get one of these for two months. When someone gets one, a dump of the SPI-NOR chip (mostly for DTB), and a dmesg (or supout) will get us started.