I have 2 of those break-out boards, 1 in ROCK3A and 1 in ROCK5B. The one in ROCK3A did not fit, so needed soldering iron to slightly modify it.
ROCK3A runs Armbian vendor kernel, there following overlay is needed:
/usr/lib/linux-image-6.1.115-vendor-rk35xx/rockchip/overlay/rock-3a-sata.dtbo
Is not available for mainline kernel.
For ROCK5B:
/usr/lib/linux-image-6.1.115-vendor-rk35xx/rockchip/overlay/rock-5b-sata.dtbo
or mainline based:
/usr/lib/linux-image-7.0.0-rc3-edge-rockchip64/rockchip/overlay/rockchip-rk3588-sata1.dtbo
or (what I do) use Tianocore EDK2 UEFI v1.1 and in the setup select SATA instead PCIe2x1 for that lane.
ROCK5ITX+ is quite new, so I think one of the rockchip-rk3588-sata?.dtbo should work. Look in blockdiagram/schematics which multiphy/lane is it, might be different from ROCK5B. I always forget the number.
Alternative is to keep function on M.2 E-key multiphy PCIe2x1 and order a E-Key adaptor with own/extra SATA chip. I have one, is 2-port JM chipset, but unused as I only need 1 SATA port and extra chip adds power consumption. Which might not matter at all for ITX board, but I use battery operation as well.
see also: Radxa M.2 E key to SATA breakout card on Armbian. HDD is not visible. [UNRESOLVED] - #23 by radrocks