There are two hoses that can be used on the grill.
This one if you want to hook directly from the RV propane output under the unit. In my case the BlackStone On the Go in the pix below.
https://www.amazon.com/dp/B09D2SXK21
You have to not connect the Blackstone provided regulator circled in red. go direct from propane line feed under the RV to the grill input.
If on the other hand, you want to connect direct to a 5#-20# LP bottle, then use this hose:
https://www.amazon.com/dp/B08P7H13Q4?th=1
Leave the supplied Blackstone regulator connected.
I suspect all the other portable griddles use the same configuration.