I keep seeing these type Anker and Harbor Freight Portable Power Stations advertised as backup power and see them being used by campers/RV'ers with solar charging. Anybody use them - are they a good option? How do you figure out what size you need?
They seem like a viable option for camping remote, but would have to be Tesla Power wall sized to do any good for home backup?

For backup power to your home? No, they aren't a good option. Would run a ceiling fan and wifi for a few hours, but that's it without more juice flowing into them. The one you linked is 512 watt hours, so that's a window unit for one hour tops.

Be way better off with a small 2kw inverter generator with a hots bridged adapter into a 50 amp interlock plug. That will run fridge, window unit, all lights (assuming led) and fans of your typical sized house.

There are some Power Wall sized options on the market with Power Wall sized pricing. I think if you wanted to run fridge/freezer, a fan, and charge/run some electronics having a number of smaller portable power stations and a portable solar array isn't a bad option. Then you also have a bunch of portable power for general use.

If you want a real whole home backup id go a different route.

And if you have gas appliances, it can run your water heater, central heat, oven, etc.

I see them on the weekend at softball tournaments. I've asked about them. Most people use them to run fans, charge phones and iPads, etc. I've seen one setup with a small solar array, and they were using it to keep the bank charged all weekend so kids could keep doing their TikToks and watching Reels.

They all had generators running their mini-tailgating setups and anything drawing real power. I would, too.

I have the Harbor freight 600 and the little 350. I used the 600 to power my Iceco 12 v fridge on a road trip two weeks ago. It powered the fridge in the back of my track from Midland to College Station with several stops and going slow about 7 hours and used only 15% off the battery. It ran the same setup later in the week at the river in Lockhart for 14 hours and only used 25% of the battery but it was in the shade versus direct sun driving the road.

I have the HF 350 watt one and like it. Use it at job sites and the like for items that don't need a larger generator.