None of the ROG AIOs have anything to connect to the motherboard's water loop telemetry headers. I looked around when choosing cooling, and there didn't seem to be an easy kit of bits to just buy and plug into the ASUS boards that have those headers. I'm sure they are out there somewhere in the custom loop world, and I did find some temperature and flow monitoring devices, but it doesn't seem like a widely available thing. I went with a ROG Ryujin II 360 AIO in the end, and it does have telemetry built in for loop temperature and pump speed (which is fed to the motherboard over a USB 2.0 header).
Honestly, I find it surprising that the likes of EKWB don't do some sort of premium kit for boards with those headers, but they didn't last time I looked.