I'm afraid we're derailing this thread, but just 2 more cents on the viewfinder app thing:
Yes, for me it's a significant drawback to an otherwise really nice app. But for many people, it won't matter, and, as I said, I'm a fan of this developer's efforts. His iOS versions of the apps don't have this drawback, and they're quite reasonably priced.
I have considered using a digital camera of some kind, as you do, Alan. However, the good viewfinder apps include a lot of convenience features that appeal to me. They can show the actual aspect ratio of film formats (6x7, for example, which I shoot all the time). The good ones allow you to limit your focal length choices to just the lenses you actually use. So when using the app with my 6x7 camera, I only have 3 choices to cycle through, matching my 65mm, 100mm, and 150mm lenses. When I switch the app to 6x6, it switches to the focal lengths I have for that format (55mm, 80mm, and 135mm) and no others are shown, so I don't have to zoom or cycle through focal lengths that aren't relevant to my 6x6 system. Many apps also give you the ability to do film simulations and add the effect of contrast filters to a b&w simulation (or even custom LUTs that you create yourself, in some cases). Of course, these are not completely accurate, but they can help me a little in some cases.
Also, folks use these apps for location scouting all the time. You can shoot a reference photo using the full simulation, and the phone, of course, can give it a GPS stamp, so you can return later (maybe when the light is better, or you have a more appropriate camera or film) to that exact spot.
Plus, I'm using the phone for other photographic things, too, so it's in my hand a lot anyway (quite apart from using it as a communication device). I have a film reciprocity calculator in the phone, a light meter (don't use it much), and a GPS navigation app for hikers, which I use to hike to locations I want to shoot. And the phone slides easily into a chest pocket in my hiking jacket, where it has essentially no bulk or weight, and I can take it out and check a composition in 15 seconds without taking my backpack off, or digging into a bag.
I should also say that my Google Pixel 4 is a really good camera in and of itself. I sometimes use it to take real pictures, even when I've got my 6x7 system with me. This is why it's such a bummer to me that there are no viewfinder apps for Android that really work well for me. I have to carry an iPhone when I'm out photographing, even though I don't use it for anything else.