Of course, everyone has different requirements on their phone, so the question if one would be comfortable running their buisness of a pine phone is quite divers.

Phone calls, texts and E-Mails

Text and E-Mails pretty much work as well as on every other phone. Phone calls work too, but the audio quality is below what one could expect from a modern iPhone.

Battery

While the battery runtime of one battery is definitely lower compared to competing devices, it is also replaceable. I usually spend my day in the office were the phone can be charged, so the battery life does not become an issue. When I am traveling I bring some extra batteries. The form factor is commonly available and batteries cost around 10 €, so I got 4 of them, which last me for ~36 hours until I have to charge them. I have so far never spend more time away from an outlet.

GPS

Works nowadays pretty reliable, accuracy of around 20 m is also good enough to find were I need to go

Bluetooth

Definitely not perfect but random disconnects happen rarely. On the other side I have an headphone jack, which always works reliably

Camera

Ok, this point goes to you, the camera is not usable. When taking pictures of documents I usually have to use my tablet.

So now to the overarching question:

Do you, in all honesty, feel comfortable enough with your device that you would confidently run a business solely through it? No, I would not feel comfortable to run a business through a phone, I need a real computer for my work. If I could only use a phone I would choose the pine phone, because at least it can run all software I require for my daily work. Connected to keyboard, mouse and a monitor it could be a slow, but acceptable work machine I can certainly imagine that there are jobs, which rely more heavily on a phone. But in these cases one should have separate work and private phones anyway