I (a non-diabetic interested in athletic performance) use an Abbott CGM sporadically and I have absolutely not agreed to any terms of service nor any other agreement of any kind - legal or otherwise.
I bought a purpose-specific, old model iphone from "Back Market" with no SIM card, very briefly allowed it wifi access long enough to download the "Lingo" app, then set the phone to airplane mode. Dedicated, throwaway email and AppleID.
It has never left airplane mode and it works perfectly. Pairing subsequent sensors does not require taking it out of airplane mode.
Further, I have no legal relationship nor have I made any agreement of any kind with Abbott.
I highly recommend that any user of these devices do the same.