I was looking at that over-the-headrest storage unit, but ended up buying one that had the covered bags up top and a second row of net pouches below the bag, so it comes closer to the floor (maximizes the seat back space). It has a strap for all 3 headrests.
https://www.walmart.com/ip/Auto-Car-Trunk-Organizer-Back-Seat-Mesh-Pocket-Storage-Bag-HFON/470734439 I have not received it yet. I like the idea of putting Velcro on the back to stop it from flopping into the cargo area, since the seat backs slope.
I also got a storage net to have on hand to catch odds & ends.
https://www.walmart.com/ip/High-Road-Clip-on-Cargo-Organizer-Storage-Net/17249000 I figure I can store it in the back-of-the-seat unit and clip it over top of that unit as needed.
Regarding your phone pouch: I was looking at these, but since I have not yet used my phone as a music machine, I just have it laying in the spot by the cigarette lighter in front of the shifter. I was thinking of getting one of these vent-mounted pouches, but I'm gonna hold off for now:
https://www.walmart.com/ip/Vehicle-...ls-Pocket-Pouch-Holder-Storage-Blue/623049912 There are lots of different versions of the pouch holders.
Since I'm helping you spend your money...here is a protective phone case that slides into a holster (sort of like Otter Box), and the phone case already has the metal disc on the back of it.
https://www.amazon.com/dp/ (commissions earned) The phone is somewhat shielded from the magnetism. I also like the belt clip on the holster because it has a tab on the end that catches under your belt so it doesn't not just slide off. You gotta work to unhook it. The case rotates on the clip (vertical/horizontal carry.) Under $20. Comes with a magnetic vent clip base. It does not hold the phone over severe bumps...I'm afraid to put a super magnet on it.
Lastly, as a fellow perfectionist, you might have ideas on where I can get a car fire extinguisher. All of the non-Halon ones (under $150) that say "car" on them also say "Do not expose to temperatures under 32 or over 100" Now, how does one accomplish that with something stored in a vehicle all year??? I actually called Kidde customer service this morning to ask that very question. The rep said "Yes, our car and marine fire extinguishers do say that on them, but lots of people keep them stored in their cars and boats all year round with no problem." So there's the written warranty, and there's what the sales guy says. And I want to make certain it's gonna work when I need it. I asked the question once again, I got the same answer, so I did not debate it. I'm still looking.