With respect to body fat percentage, I would caution being conservative with your goals. I don't know your personal situation, but my experience with this area led me to a powerful conclusion in 2019: Fitness has diminishing returns as you get to the more extreme ends.
For me, getting from 20% to 15% body fat was straightforward, and took 3 months. I figured 15% to 10% was achievable in a similar timeframe, but it ended up taking twice as long, even with careful dieting and exercise. I would imagine 10% to 8% or 7% is even more difficult to achieve (and maintain).
Fitness is strange - everyone's bodies are different, so your mileage may vary. Although I do believe the concept of diminishing returns plays out in a general manner. Good luck on your goals!
Coming from someone using an S7 Edge since its release, I don't think it would be an upgrade for me. I'm losing more than I'm gaining, I don't think I can go back to a non-waterproof/water-resistant phone which doesn't have wireless charging.
From an S6Edge+ perspective, if you're missing out the latest software updates and need an upgrade in the camera department, then go for it. Otherwise, there may be a better choices in the market or just go with a "premium" smartphone to future-proof for another 3-5 years.
