Indoor disconnect minimum distance

I’ve done a lot of research and I’m trying to figure this one out. I have 2 200 A breaker panels.
I wanted to install an indoor disconnect GF224N which will be in between the grid and the breaker panel

Is there a minimum distance that I have to maintain between the breaker panel and the indoor disconnect? Obviously the grid is on the outside and the indoor disconnect and main breaker are going to be on the inside.

I read somewhere that there is a 30 inch minimum distance between the electrical panels and any devices, however my electric panels are adjacent to each other and they don’t have 30 inches in between them so that was confusing

I’m hoping I could install the indoor disconnects right below the main breakers so I can run the 4/0 wires in the drywall and bring them into the disconnect.

Any help would be greatly appreciated. Thank you.

30" of clear left to right access space in front of each. (From floor to ceiling)
But they can share the same space (overlapped), as long as they don't hender access to each other.

Thank you so much!

The 30" is for a person to have access to the panel.