Am looking to fly fpv over parts of the Peak District, authorisation pending
not sure about where your at that you can get authorization to fly BVLOS, but if your going to break VLOS, your going to want an actual long range prototypical like ELRS or cross fire.
I think I have seen people get maybe a mile out of something like what you have there, but that was not with a AR620, but something with an external antenna.
Also at these frequencies, anything between you and your craft (trees, mountains, hills, etc) massively drop your signal. For context, I got a bit of hill between me and my fixed wing once (wasn't paying attention to the terrain) [that or a metal truck and my water filled body at the very least - or all of the above.]... was close enough that if I could have seen my craft to fly it LOS (and it is backpack sized). and almost dropped my control link with ELRS, had I been on spekrum, I am sure it would have dropped.