Don’t mind Re5et, as we’ve learned from my ‘Before making music’ thread - he’s probably just feeling a little salty from life and needs to unplug and ‘touch grass’ as the children say today.
As for what you are trying to accomplish, you’ve got 90% of what you need.
Apple brand lightning port USB dongle for the phone (yes, buy the more expensive apple brand) with bigger one with charging port so your phone can stay charged while filming.
You’ll want OBS on your Mac - may as well uTube some ‘OBS for beginners’ videos as this will be the hardest part to learn, but it’s not overly difficult. Will just take a couple hours of study then same amount of trial and error.
As stated above, all your music audio will go thru the SP as an audio interface, no need for anything else.
The two biggest concerns will be your audio if you choose to speak about the process, and lighting the SP correctly/aiming the phone/camera properly as an overhead shot if that’s what you have in mind.
iOS app for filming I would suggest Filmic
Start with the OBS videos, (your smartphone can be wireless into OBS with a free app/web host)
I’m off to work but will happily help in the following days/weeks.
I’ve done some music uTubing. It’s fun.
Edit - you can certainly not use OBS, and just record then edit and edit, but OBS will help in the long run as you do livestreams, want multi camera (phone and tablet) shots, record onto your Mac instead of the phone then transferring etc.