Given the large number of flowering things surrounding RedQuarters, we tend to have lots of pollinators hanging around, along with butterflies and the occasional hummingbird. We help this along by providing quarters for native bees.
The one with the little overhang is store-bought. DadRed made the others. As you can guess, there’s not an overwhelming amount of work or skill required. Or you can buy them from a number of commercial outlets.
You note that these are not true hives for communal living, such as those used by honey bee raisers. Our local native bees—leaf-cutter bees—are “solitary,” meaning that each female builds her own little nest for the egg and pupa. There’s no queen, no swarming, and no large hive. Instead they look for the proper sized hole and do their thing there. If you look closely at the photo, you can see that a few holes look plugged. Those are bee nests, soon to produce a new generation of bees.
Bee houses should be on south-facing, sheltered spots if possible, as the above are. This keeps them out of the weather and warm. The bees do not produce honey, but they do pollinate various plants. This is a very good thing.
The native bees found in my region are smaller than honey and bumble bees, and do not sting. They just do their thing and ignore people. There are apiarists within a few miles of RedQuarters, and I have seen honey bees and native bees on the same plants, ignoring each other.
One difficulty you may have is that if you want to encourage native bees and other pollinators, you really shouldn’t spray insecticide in your garden. At RedQuarters we use nemotodes to prevent grubs, mosquito dunks in the cisterns to keep the pests at bay (with occasional drops of mineral oil to smother the little [redacted] while still larvae), and a soap and water blend for aphids. When we do spray (aphids and the occasional wasp nest, and Black Widow spiders), we try to use the minimum amount of spray and target very carefully. Thus far it has worked well for us.
Oh, and wasp traps. Those keep the predatory wasps from going after the butterflies and bees.
Some sites recommend using paper tubes and other disposable materials in order to prevent the spread of disease. I’ve not had that problem yet, so I don’t know how much to worry about it. Our bee boxes seem to work, and we have lots of bees, so it may depend on species and location. Your local ag-extension agency or apiarist club (that’s bee keepers) will have information for your area.