Question about eMMC support and SD card support


I see that there are two eMMC connectors (J9, J99). What are compatible eMMC modules called that have two connectors? Is it backwards compatible with modules that only have one connector?
Should I look for HS400 or eMMC 5.1 module, or something else?

And secondly about the SD card slot: What are the fastest cards, that are supported? UHS-I, or UHS-II?

Thanks in advance!

I use a 32 GB, 5.1 eMMC for the Rock Pi, ALLNET article no. A158777. I think only J9 is electrically relevant. J99 is for mechanical protection, so that the module does not wobble, but sits firmly.
VisionFive 2 Design Schematics

Schematic of ROCK 4 model A | B


See section “2.2.5. SD/MMC Interface” of the JH7110 datasheet
For SD cards the fastest supported should be UHSI_SDR104 @ 104 MB/sec followed behind by UHSI_SDR50 (or UHSI_DDR50) @ 50 MB/sec