I don't think anyone's description here provides justice to how good this bag really is. I received mine a few days ago but only just got looking into it. Its extremely well laid out, has pockets, zippers and space for a whole lot of stuff...
Lykus M1 Pro Backpack 2022 Edition also works.
Originally designed for the Mavic 3 with RC Pro.
Just need to remove the stiff upper foam piece to make room for the larger Mavic 4 Pro.
https://www.ebay.com/itm/396416167338
That is what I thought might be required. Arm mounts are less convenient, more expensive since four might me needed and tend to be more directional. It will be interesting to see what is developed that doesn't interfere with the sensors or camera.
I use a guy on etsy and he's only putting out arm mounts. Said something about the way the M4P is he can't find a location on the actual body to mount a strobe