A happy Xperia X + Sailfish OS user here (v 2.1.4.14). I believe the points below apply well before 2.1.4. My only gripe is old browser engine; for now I end up opening some apps via Android Firefox (59), with decent performance.
>tethering
USB tethering requires manual installation of a Sailfish package via CLI
>wlanaccess point
works out of the box
>bluetooth
works out of the box: A2DP, file & contact transfer, perhaps more I haven't tested yet. Works just fine old Nokia headphones, and with Roidmi via the Android app.
>tethering USB tethering requires manual installation of a Sailfish package via CLI >wlanaccess point works out of the box >bluetooth works out of the box: A2DP, file & contact transfer, perhaps more I haven't tested yet. Works just fine old Nokia headphones, and with Roidmi via the Android app.