I have seen some other peoples set up including a very nice 3D printed holder which was very compact and held a small power bank. This holder however is not compact LOL! and it cost £29.99 GBP on Amazon. The power bank goes in my pocket. Holding it with 2 hands gives me a little more control of my aiming, yet can also be used with one hand when needed. Also i can set it down safely.
I’m using a Samsung S21 Ultra connected with a Y USB-B splitter cable. It might give some other ideas for your own hand held solutions.