The Peak Design Everyday Sling 6L is basically perfect for the a7IV—I used it for a month and it fits 2 lenses easily. For power, i actually recommend this combo: * Nitecore USN4 Pro Dual Slot USB-C QC Charger
* Anker 735 Charger (GaNPrime 65W) It's way smaller than the stock brick and i dont have any complaints, worked well! peace.

Sooo basically I went through this exact same spiral last year trying to find the best balance between price and performance for my a7IV kit. Honestly, I spent way too much time doing market research on bags lol. I looked at everything from high-end stuff to budget options, and in my experience, something like the WANDRD Rogue 6L Sling offers a lot more rugged protection for the money compared to some of the softer street bags I've tried. Plus, it fits the sensor-heavy Sony bodies like a glove. On the power side, I actually stopped carrying a wall charger entirely. I shifted to using the SmallRig NP-FZ100 USB-C Rechargeable Camera Battery because you can plug a cable straight into the battery itself—it’s sooo much easier for light travel!! Quick tip: pair it with a tiny Anker 511 Charger (Nano 3) and you wont even feel it in ur bag. Hope the trip goes well, seriously jealous! Peace.

Seconding the Nitecore advice, it's a lifesaver. Over the years I've found the Bellroy Venture Sling 6L is actually a bit more low-profile than the PD for street shooting. To protect that sensor, definitely pack a Giottos Rocket Air Blaster Small. Also, ngl, the Sony NP-FZ100 Rechargeable Battery is so efficient you really only need two for a whole month if you're charging nightly. Enjoy the trip!

Facts.

So basically the consensus is that 6L slings and USB-C PD are the way to go for the a7IV. I just stumbled upon this and honestly, i learned the hard way that cheaping out is NOT the move. I've had issues with budget bags before—one literally fell apart during a trek... sooo frustrating. I thought I was being practical but it cost me more in the long run. ur gear deserves better. anyway, gl!

I have spent a lot of time dialing in my Sony travel kit and I am honestly quite satisfied with the current state of my gear. I have found that a bit of a DIY approach to the internal layout makes a huge difference in how much you can actually carry without adding bulk.

• Look into the sling bags from Shimoda because their build quality is exceptional for outdoor use.
• Any high-output power bank from Baseus will serve you well for keeping that a7IV topped off via USB-C.
• Use some simple padded wraps from Domke to protect your extra lenses if you are stuffing them into tighter spots. This setup works well and I have had zero complaints during my last few months of travel. Staying light is mostly about being methodical with your organization and choosing brands that prioritize durability.