For one, meshroom is frustrating. I have used both reality capture and meshroom and reality capture is much easier to use overall and probably 100x faster.
Regarding your iphone, are you using some 'pro' mode? What I mean: is your exposure, white balance, shutter, fstop and iso in a locked position or do these change per shot? My recommendation is keep them locked entirely and move the object on a lazy Susan. Excuse my naivety I have never owned an iphone.
Secondary yes a DSLR is much better especially if the software recognizes the camera and the lens this way it can auto remove distortion. This doesnt mean you need 'raw' photos, jpg is fine (in fact better for computation speed) however I say this because I know how to manually control the settings on a DSLR so if you can do the same with your phone, and the software can remove distortion it should be ok.
Lastly, it took me about 6,000 photos and about 2 weeks of daily practice and different setups until I found one that worked well for me. The best setup for me is a black clad background, black clad lazy Susan and nice diffuse lighting (overcast/softbox) to get the images stable. Black clad = black fabric with very little reflection, this way you dont need to do any masking and less cleanup. If you also plan on capturing the bottom section you will need to flip the object 90 degrees and do the whole process again, 360 degrees of photos front level, 360 degrees top level looking down, 4 degrees rotation per photo does a good job. You can then stitch the two captures together to capture the object 360 degrees using markers or if you did a good job with the photos it should do it automatically.
