302boot-lvm.img imo is for 3.0.2 version and it was uploaded 18.03.2019 also no idea about lvm boot, only tested it myself just once when first released, but i can say ext4 is works just fine on my jolla 1 you can try flash btrfs image first and check everything works or not also wifi problems was happened ages ago when users used mmcblk0p28 dumps for unbricking, usually reinstalling kernel packages via mobile network helps