I've been using Sleephead for years and now its Oscar, same thing but probably updated. I also use my Oximeter from time to time. Yes Oscar does allow to download from certain Oximeters. HOWEVER, if your a mac user and running a later OS than High Sierra you may have problems getting a driver so it can recognise the Oximeter. Its a bit complicated for Mac users as you still need a driver for the earlier OS as well. The makers of most Oximeters, Contec, do not supply reading software for Macs. I read it in my Oscar software but as I said for mac users its not straightforward.
I can sync the timing of the Oximeter to the CPAP time so I can do direct comparisons to what the CPAP machine has recorded at the same time. By the way my second iMac runs Snow Leopard, for that OS you'll need the old Sleepyhead software as Oscar doesn't run on Snow Leopard.