u/Similar_Ostrich2620

Hey, I'm in the process of looking at degoogling where possible and also trying to offboard from the corporate overlords where possible. I am a tech with good "google fu", but I've never really looked into non AU based phones and understanding radio/mobile networks.

I currently use the Samsung FE 23 it's been a reliable phone but I'm not a fan of all the extranous samsung/google shit. I have a few requirements and just wondering if anyone is able to verify what is/isn't capable.

1. Does it work in Australia? I'm currently with AussieBB (optus reseller) but regional WA only gets Telstra reception. Some people posted elsewhere and said it works with optus so I'm assuming AussieBB should be fine being an optus reseller, but what's the chances of Telstra working?
2. I have a personal medical device (sensor) that connects and is monitored via the phone (uses NFC to initatiate and connect via bluetooth). The official company supported devices are pretty limited, but that's mostly becuase government regulation and testing takes ages for devices to get officially approved. I'd prefer to get the Murena e/OS but not sure if the OS would be compatible. There approved OS's are pretty much just apple and android. The specific app is the Librelink (or alternatively dexcom) if anyone knows if that works with Murena e/OS otherwise I guess I'd have to go with there android OS :(
3. Does anyone know if the cardholder backing blocks/interferes with the NFC scan, as per above I need to use the NFC scanner to start the connection with the sensor every 2 weeks, and currently I use a magentic card holder so I can remove the card holders to do an NFC scan with the phone, but I've had other cases where the cards block the NFC scan so I'd have to remove the case everytime to complete the connection.
4. Is the e/OS much different from android? Like the difference between Mac and Windows or is it pretty much android with all the tracking removed?

Edit:
The repairability sounds nice but would I really just be trading being locked into samsung for being locked into fairphone? Is there third party parts for fairphone, or is it really all just coming from fairphone?