I use my iPhone X almost exclusively, and it has a really good camera which works well for almost everything you can think of. I make observations using the iNat app. I carry a very cheap clip-on lens, which I sometimes use for macro shots of lichens etc.
(I must say one thing though, most of my attempted bird photos are not good, unless the bird is quite large, or is not easily spooked around people.)
I also do own a RG-5 which is great for macro work, but using the iNat app on the iPhone enables me to get lots and lots of good observations, often a couple hundred in just two or three hours, without a lot of fuss or work in terms of uploading and so on.
I also like that I don’t need to take a lot of photography equipment out with me.
Basically with photo observations, you need to choose between quantity and quality. I find that the camera in the iPhone X (which has several great features including some optical zoom and some digital zoom) gives me fairly excellent quality by cell phone standards, and enables me to rack up as many observations as I like in a short time and upload them with no sweat.
One drawback is that the iPhone stops working temporarily if you are holding it in your hand outdoors for hours in extreme cold or extreme heat. In the worst part of winter I sometimes have to stuff it inside my clothes, close to my body, to get it warm enough to work again.