Amazon.com: Anker Portable Generator for Home Use, PowerHouse II 400, 300W/388.8Wh, 110V AC Outlet/60W USB-C Power Delivery Portable Power Station $299

Yeah in general, you want to avoid the DC -> AC / AC -> DC conversion process as much as possible, given the losses involved. Nowadays you can indeed find DC versions of a lot of appliances, and for any DC devices that normally rely on a wall wart (AC adapter), up to 100W, you can bypass the wall wart and use USB-C Power Delivery, which is a great standard allowing for negotiated 5/9/12/15/20V output (or custom voltages in between, using PPS) at up to 5A / 100W. A lot of devices (from phones, tablets, and laptops to even electric toothbrushes, screwdrivers, etc.) use USB-C PD now, so there's no work required there; for other DC devices, you can use a USB-C PD sink (which takes USB-C input and gives you a DC output at a certain set voltage). The r/UsbCHardware [reddit.com] subreddit is a good resource there.

In a van context, you'll probably still need an inverter, to handle any remaining AC appliances and to give you extra AC outlets for any new devices you happen to need to plug in, but if you design everything prioritizing DC, you can reduce your inverter usage and increase overall efficiency as a result. A lot of Sprinter-type RVs are outfitted with large battery banks + more solar to allow for more free usage of the larger appliances (e.g., A/C, induction cooktop, etc.).

Propane is of course much more energy-dense than current lithium batteries, but you find an increasing number of propane-free builds (due to the safety issues with propane and the need to periodically refill), made possible by a combination of electric appliances and, where you just need heat, tapping into the vehicle's primary fuel (e.g., diesel cabin heaters). In the near future we'll also start to see more fully-electric camper vans (i.e., EV van conversions), where you have an enormous battery that everything ties into (enabled by a combination of large solar + L3 EV fast charging).

MatKyne raises a valid point about the wire thickness required to carry high current levels - you can transmit huge loads over 120V AC with much thinner cabling vs. with 12V DC. That said, there are ways to address that on your longer runs in an RV. For instance, if you have a heavy-duty alternator up front charging your house battery pack in the center/rear of the van, that's a pretty long wiring run, normally 12V DC. One way to address that (which is happening in the auto industry more broadly as well) is to instead jump to 48V DC.

Thanks, very helpful & informative and just what I was looking for. This is all VERY preliminary, as I have no immediate plans of getting or building a camper, but maybe someday, and since there's often a long design process before undertaking a custom build, it never hurts to know as much as possible ahead of time. Ideally any camper I'd live in would be 100% DC, but I suppose it's nice to have some AC for whatever, and a modest inverter makes sense. You don't have to actually use it most of the time if you don't want to. AC's main benefit was always in long distance transmission, but DC is usually more efficient for most loads. A lot of people don't realize that many devices they use that plug into AC outlets actually work on DC internally, and use adapters to convert AC to DC. If one can avoid the efficiency loss in conversion, it's preferable, especially in a a van where every amp hour is precious.

Even then, it is not actually generating power. In your example, its the solar panels which are the generators with this device simply storing the power.
This is a battery, no ifs ands or buts.

Even then, it is not actually generating power. In your example, its the solar panels which are the generators with this device simply storing the power.
This is a battery, no ifs ands or buts.

I'm not sure if MatKyne's other point is being missed - plugging into shore power, assuming you are not planning complete off grid living, means your appliances can run off AC power natively. When plugged into shore power and your appliances are all DC, you will need an inverter to convert shore AC to DC. Also, heavier gauge wires foot for foot increases up front costs (even if incremental) and weight which saps already poor fuel consumption on RVs.

If that's your line of reasoning a real generator isn't a generator either, it's merely a way to uncharge all the stored sunlight from the plants and algae that we dug up from the ground into power.

If that's the case then name a "true" generator. Only nuclear would qualify for that as it actually does create energy, from matter, per e=mc2. All other forms of energy "generation" merely transform one form of energy, be it wind, water, chemical, mechanical, heat or solar, into electrical energy. And yet we've been calling devices that transform certain kinds of energy into electrical energy using electromagnetism generators, alternators and dynamos for around 200 years. Hell, even nuclear doesn't "generate" electricity. It generates heat, which spins turbines, which spin dynamos, which output electricity. Ultimately, it's all semantics and what we choose to call things.

If that's the case then name a "true" generator. Only nuclear would qualify for that as it actually does create energy, from matter, per e=mc2. All other forms of energy "generation" merely transform one form of energy, be it wind, water, chemical, mechanical, heat or solar, into electrical energy. And yet we've been calling devices that transform certain kinds of energy into electrical energy using electromagnetism generators, alternators and dynamos for around 200 years. Hell, even nuclear doesn't "generate" electricity. It generates heat, which spins turbines, which spin dynamos, which output electricity. Ultimately, it's all semantics and what we choose to call things.