Those are really cool. My company has about 25 of them.We use them to run tests and check faults on the old Arrow III rail cars. They were computerized in the mid 90s. We use Kermit as a terminal program. Almost any terminal program will do, like Hyper Terminal.
I've always had more that one smart phone at a time so my list will be somewhat weird.
Galaxy S3 (work) and S4
Galaxy S5 (work) S7, Note 7 (Had to return 3 of them) and iPhone 7 after returning the 3rd Note 7
Galaxy S7 (work), S7 and iPhone XR
Galaxy S20, Galaxy S10E (work), iPhone 11...
None of the bunch of CDs I ripped into iTunes over the years will automatically download onto the phone. I have to sunc it to the PC. But, once I get a new iPhone and do a side by side transfer, it will all be there. It's definitely a flawed setup but I bought into the iTunes world a long time...
It's not that cut and dry in the Apple universe. You have to use iTunes in order for you to do that. Your other option is to buy everything thru iTunes and everytime you upgrage to a new iPhone you stuff will just download onto the new phone.