I installed SailfishOS last week on an Xperia iii - I checked it with a minimal install and was pleasantly surprised to see ~ 33% battery after 2 days, so I guess 2.5 to 3 days.
This is about the same as my previous Sailfish phone, a Gemini X27 PDA, which I am replacing because it does not support 4G and my MSP (Vodafone UK) is actively shutting down 3G.
The only problem that I have found is that I cannot send SMS when the phone 4G (beta) is enabled - making and receiving calls and receiving SMS are fine.
My workaround is to disable 4G, send the SMS and enable 4G again.
The GPS works and I am running Pure Maps with the HERE map provider - I have not used it in anger.
The Android support is a nice to have as I now have microG, Kindle and the Vodafone app installed.
By the way, Sailfish was installed over the Android 11 that the phone came with, as there were no updates available over the air - it was not Android AOSP ( release number ended in .9? with tag release-keys?).
I have found no problems with doing that.