I don't know what the status is on the S5 Active in particular, but the S5 is/was one of the most highly used and well developed of all Cyanogen/LineageOS phones. All the rest of the Samsung phones after the S5 had locked down bootloaders and other crap, but the S5 has incredible support. You should definitely go find out what the status is on it. The S5 Active probably has some minor differences that requires a specific image version but I don't know.

And if you don't want to mess with it yourself you could probably sell it for $80.