Some may not agree to that, but we consider a decent Camera as an essential piece of equipment for adventure cycling.
A bicycle tour is often among the best times of our life, taking some memories with you is something you’ll hardly regret, will you be happy without pictures of your wedding?
I’ve met many people who first thought they will be fine with their phones and maybe an action cam, like a GoPro or such, most of them regretted this choice and bought a decent camera as soon as they could. We personally use a Nikon D52000, after our Panasonic Superzoom failed.
We traveled for one entire year without a smartphone and we survived. Anyway having a modern phone can help you keep in touch with your people, find hospitality on Couchsurfing or Warmshower, post on social networks, and so on.
We have two XiaoMi RedMi4, which we like a lot. They come for around 100$ (we bought them in China), have a surprisingly good camera, and a sealed case (one I dropped mine in a bucket full of water and it survived, perfectly operational).
If you have a dynamo hub, why don’t use it also to charge your electronics? There are a few chargers on the market that will do this job, like the Supernova The Plug III or the cheaper BioLogic ReeCharge Power Pack.
Another way to charge your electronic equipment while cycle touring is by using solar chargers. There are brands coming out with new products every month, and solar panel efficiency is constantly improving.