Since j5nlte, j5ltechn and j5lte are currently on Oreo, it’s probably not a priority to upgrade them to Pie. But I still ask for the upgrade to show at least one person is interested.
I don’t think this phone has one day been supported by LineageOS. So I redirect to unofficial builds :
@Anonyme, Samsung’s Galaxy J5N LTE “j5nlte” SM-J500FN supported by /e/ OS is not subject to the risk of “the anti-rollback thing” because the latest StockROm Android 6.0.1 does not support the bootloader and modem issues of StockROM Android Oero 8.0.0 devices such as the Samsung Galaxy A5 SM-520F.
On a S5 SM-G900F, also last StockROM version Android 6.0.1, I already tried all possible custom ROMs. For example LOS 14.1, 15.0, 16.0, 17.0, but also others. One and the same bootloader/modem version from stockROM 6.0.1 cooperated with all custumROM versions without any problems.