Originally Posted by olf

As most people want to run Android apps, but also many people want an alternative to Android, there are really only two options:
a. Dual-Boot with LineageOS and SailfishOS (the latter maybe optionally due to license costs)
b. SailfishOS with AlienDalvik
... and the combination of both:
c. Dual-Boot with LineageOS and SailfishOS with AlienDalvik

Note, that a properly working dual-boot setup can be a challenge of its own (technically *and* WRT usability), so perusing b. first makes most sense, IMO.