Let me share a little bit about myself first. My apnea treatment started with a blast, but after adjusting my settings I couldn't get as good sleep as during my first night with CPAP. Since my AHI was all ok, I started to look into O2 saturation monitoring.
I have tried O2 Ring, but after it's battery didn't last even 2h during my sleep I developed distrust on Viatom suppliers in my country. My doctor suggested that I don't need very accurate device right now, so I should take a look into some kind of fitband. That was exactly what I did and I find some youtube channel that suggested that fitbit has pretty accurate sleep phases detection. Since I couldn't find any data about SpO2 accuracy, this information along with ability to export data through Google Takeout made me buy Fitbit Inspire 3.
I have made an account here specifically to share with you my python script, that I have worked on last week to transform Fitbit data into Viatom SpO2+HR and Dreem sleep phases files. Now with all data in OSCAR I find it easier to adjust my CPAP settings. Maybe someone will find it useful, I have shared it on my gDrive: https://drive.google.com/file/d/12bb0a_nW6s0hrm2cIdUw5FuvZW-SLT17/view?usp=drive_link
Since I am a C++ programmer myself, would you accept change that adds Fitbit import directly in OSCAR? For my use it is easier to use script than OSCAR fork, but it there is a possibility that it would go into official release, then it is worth an effort