Scenario: you get a Oneplus 5T and install LineageOS 15.1. How well does the camera perform compared to the standard one? Does it support dual camera’s and all?
What do you mean with “dual camera”? Is this for camera at the front and back? I think it works just fine since they more or less use stock-android.
No, it has dual camera’s at the back, that optimize pictures by combining the images using software.
My bad 
Well, I think it should work but it’s best to take a look at the XDA forum.
The V20 has 2 rear cameras, but their images aren’t combined; one is a wide-angle lens and gets a different picture from the standard one. The stock camera app supports all 3 cameras but the other camera apps on the play store don’t support them. It’s also not possible to sideload the stock camera app for some reason that goes over my head because I’m a scrub.
So I think the support depends on how much attention the developers for your phone have paid to the camera, which is hard to predict. You could ask on XDA probably. In my experience with Lineage, uncommon hardware features are usually not supported super well (see quad DAC, second screen…feels bad man).
I have an htc m8 with lineageOS on it and with the stock camera app there no way to utilize the second back camera functionality as far as I can tell.
It is going to depend on your hardware as well. The most popular phones often times get really really good support, and then middling support for anything that doesn’t move a ton of units.
Wouldn’t be surprised if you have to decide on either dual cameras or lineage.
Lineage has a hard enough time dealing with a single camera on phones that sell well. When I use Lineage’s default camera app on my Galaxy S7 the flash just doesn’t fire at the right time, meaning that photos in the dark are simply impossible. Not a big deal for me as I barely ever take photos to begin with, but I can imagine that this would be an issue if you actually care about the camera.
Does that change if you use Open Camera for example?
I learned the Oneplus 5T stock app can be sideloaded if you have root access, but that consistenly breaks my home banking app.
OpenCamera gives a “serious camera error” roughly 2 out of 3 times that I try to take a photo. When it does work, it works fine and the flash is timed correctly.
I use the default camera app for anything that doesn’t require the flash. The picture quality is just better than any other app I’ve tried.
When it’s too dark, I switch to the “Simple Camera” app which turns the light on all the time.
I really should invest some time into finding a good open-source camera app for my phone, but the camera really is very low on my list of priorities.
Damn that sucks. Thanks for the provided feedback!
Weird, guess there’s just problems abound when it comes to cameras on lineage, my LG G4 was pretty much useless for photos.