Question What is max practical distance from wireless AP?

There is no theoretical answer.

It depends on the specific physical variables (walls and other abstractions) and electrical noise of any specific environment,

To way to resolve is by actually is to try different Temporary location setting and choose the one that works best.

No vendor will give you theoretical distance. The longer the distance, the lower speed it gets. Vendor doesn't know what device you use and how much bandwidth the device needs. A device that only needs very few bandwidth can be placed more far away from the router or AP. You can choose lower resolution for cameras and put them at a further distance.

You also knew that your environment affect the result a lot. You can only test yourself.

Besides the physical layout there's also the signal whether you need high speed 5-6Ghz or you just need connectivity on 2.4Ghz. Low band will get you distance / penetration through objects.

I have a single AP covering 1300sq ft just fine w/ drywall and steel studs but, if someone had concrete walls it would be much different possibly requiting 2-4 APs for the same coverage.

Get an app for your phone and walk around with it and see what kind of signal you get on each band.

As has been stated, there are too many variables involved which is why nothing states a distance rating. On top of the ones people have already stated, you have hardware considerations and interference considerations. The best range will come from high gain directional antennas on both the client end and the AP.

People were using cheap pringles cans (and some threaded rod, some washers, and some plastic spacers) back in the day that they ran some wires and soldered them on to a connector that would attach to their wireless cards and/or access points and then could aim them out the window to get to free wifi that a hotel might have setup a couple miles down the road.

I can't find some of the original articles (because these were before the dot.com bust), but here is one claiming to be a 10th anniversary article (https://makezine.com/article/home/food-beverage/pringles-can-antenna-turns-10/), but I can tell you they are a couple years off since we made them in our dorms in college in 99' when there was a test installation of wifi in the engineering college main classroom building. I bought my first laptop that year because of wifi.

On top of specific antennas being used, other variables such as transmission power, interference from other networks/devices/noise, the specific frequency bands being used, how many antennas the client and access point have, if beam forming is in use, all play a role as well.

So as to your specific questions about wifi camera's and what you should do, well, it comes down to simply trying the device and seeing if it is in range with high enough bandwidth. If it isn't, the next step is to try adjusting existing antenna on you wireless access point to see if you can get better coverage, as well as check to see how many other people are using the same wireless channels you are using and attempt to get onto a clear channel (hard to do now with the newer standards using three channels simultaneously in the 2.4ghz band when there are only 3 channels that can be used that do not overlap with each other, so everyone uses the same 3 channels (in the USA that is)).

If you still do not have coverage, you might have some options depending on your wifi router to change the antenna's in use (not all will support this, and in many cases to really do this you will also need to be able to control other parameters such as transmit power). You will need to do some research into your wifi router/access point to figure out if it is possible, and what other things need to be considered (such as the use of beam forming, and even mu-mimo as you might not have the correct hardware antennas to support those functions).

That all being said, if the above does not let you connect to the wifi cameras in the locations you have installed them, you will then need to consider setting up additional access points to extend your range. I always recommend using hard wired access points and not using "mesh" networking. The "mesh" devices will just use up more of the limited wifi bandwidth that you have available to deal with repeating the data across the wifi network to the other mesh devices. It "can" be useful when you can't run a wire, but it is not otherwise recommended (if there was additional, dedicated wireless spectrum that is not shared for wifi usage that could provide the mesh network links, this would be a more useful tool, but the reality is that the bandwidth would still be better off as merged into overall wifi spectrum).

For figuring out where you need or should place your additional wifi access points, the best method is to simply test it before having the wires pulled by just using a 50m cable that you just run inside the house through doorways/up or down stairs etc., to see where placing that second or third access point will provide coverage the cameras. Alternatively, look into replacing the wifi camera with a wired one and run a wire to them (obviously not easy for cameras that are around a property and away from the house itself).