When it comes to the Custom ROM, LineageOS is the most popular and one that has an active development community. The latest LineageOS 15.1 being based on Android Oreo 8.1 packs all the goodies of the stock AOSP Oreo along with plenty of other LineageOS proprietary features. Hence, an official LineageOS 15.1 support for a device is something that it can boast of. In fact, the LineageOS team has been working hard to bring the LineageOS 15.1 on as many as devices possible. In latest, Moto Z2 Force and Sony Xperia Z2 are getting the official support of the LineageOS 15.1.
Since both of the devices are new, probably running the official Android Oreo given by their respective manufacturers, the LineageOS 15.1 is the first official Lineage ROM ever for them. However, the status of the ROM builds are experimental for both of the devices. Hence it’s almost likely to encounter some big bugs that may render the builds useless as a daily driver. What better can we expect from an initial release of a software? Of course, that is normal.
Surely the LineageOS 15.1 builds for the Moto Z2 Force and Sony Xperia XA2 will become more matured soon or later. The maintainers of the ROMs ought to roll-out OTA updates fixing most of the bugs that are currently known or reported. Nevertheless, if you can tolerate the bugs that are present on the experimental build, you may try the LineageOS 15.1 if you own either of the devices.