I installed LineageOS on my OnePlus 6 also because of lack of software updates.
My experience was mixed: it works great, even my banking app. *Except* for the camera. The default camera app took blurry pictures; Google Cam from the app store cropped significantly from the preview; and the custom Google Cam made for OnePlus 6 couldn't use the front camera.
No amount of tweaking gave me anything close to what the original OS had.
In the end my phone's camera is one of the most important features, so I got a new one.
