I too had this question, hence arriving here, and through further searching I think I found a fairly concise answer to the particular worries I had about leveraging Flutter and Unity 3D’s “unity as a library” feature.
I was wary about any performance issues that might be experienced embedding Unity into flutter, from both a performance and resource point of view. Having succesfully embeded Unity as a library into Flutter a while back, (and displaying a 3D box) for a POC i was happy with the technical/programmical issues I may encounter, so it really was only performance issues I was unsure off.
What I wasn’t sure of was if building a fully fledged flutter app, with embedded Unity cause a problem from say an FPS or memory when combined with the UI rendering done in flutter. As such I was looking for examples, medium articles, forum posts on other peoples experiences.
Below is an article covering the use of Unity as a library embedded in Flutter for a very well known brand, Aardman animations (of Wallace and grommit fame). If its good enough for them, its good enough for me. ( I was also part of the same company/group as the developers so i know they’re all really good).
It covers some of the pitfalls of embedding Unity into Flutter and what to watch out for, as well as some links to public domain libraries to use. Something i’ll be looking at leveraging myself.
What i would say, is that the general advice is to carefully manage your unity scenes, loading and unloading scenes and resources carefully to ensure you don’t hog resources. You may also have to consider what resource the lightship SDK introduces and determine how best to manage those dependencies.
Additionally it looks like there were some comms issues to over come between flutter and unity, which they’ve explained and provided a package for.
For my project, the AR part is an accompaniament for a bunch of mini AR experiences, that i can load in on demand. I.e. the AR part isn’t part of the primary experience. If the AR part was the main experience, then i might reconsider using flutter and instead just do all of it in Unity. But that isn’t the case for my project.
Hope that provides some insight into how reliable flutter, Unity and Lightship might be. You’ll have to make your own call for your specific project.