I looked into all of this. Problem is, some of the connectors you find at the RV store don't actually connect to the one that is plumbed into the RV. So you either make multiple trips to multiple stores or you end up spending way too much time on the internet searching for the correct fittings.
Next you have to either buy a grill that it is easy to remove the regulator (which may not be the grill you really want) or figure out how to disable (drill or otherwise destroy) the regulator on the grill. So, to use the "nifty" good idea coupler is a PITA.
On the other hand, while you are at the RV store, you can easily pick up one of these:
https://www.campingworld.com/propane...with-handwheel
and this:
https://www.campingworld.com/12-prop...-with-acme-nut
Easy, quick and foolproof.