According to the makers of LineageOS, there were about 800,000 devices with official LineageOS team builds in use by December 2018.
The LineageOS-Team has an average of two maintainers working on one device (some devices have three maintainers working on them, some have only one. Several devices are handled by one and the same maintainer). The community of supporters is huge, and the feedback is correspondingly large. This means that the LineageOS Project has several hundred dedicated users working together.
¹That’s really a small team for about 92 smartphones and 2 laptaps.
This is the way to go. The testing community should be much larger. I applied for several devices as testers today.