

Are there any downsides to this? There has to be, right.
SailfishOS userland is proprietary software. AOSP is more open than SailfishOS. The Android compatibility layer of SailfishOS is based on AOSP, so the stack to get the most important 3rd party apps working relies as much on AOSP as any Android ROM.
Upside of SailfishOS: There is a decent chance that the upcoming Linux ARM version of Steam + Proton will run directly on that device.


















There will always be limitations unless massive changes occur such as Google open sourcing their Play Services as part of AOSP. MicroG has limited resources to implement compatibility.