One of the interesting characteristics of the Ego Tunnel is that it creates (as Finnish philosopher Antti Revonsuo called it) a robust "out-of-the brain experience", a highly realistic experience of not operating on internal models, but of effortlessly being in direct and immediate contact with the external world - and oneself.

All attention is introspection.

As a first-order approximation, I would say that phenomenality is "availability for introspective attention": Consciousness is a property of all those mental contents to which you can in principle direct your attention.

The self is not a thing, but a process.

As a philosopher, you define constraints for any good theory explaining what you are interested in, then you go out and search for help in other disciplines.

I believe that if we would carefully apply the distinction between transparency and opacity to the different layers of the human self-model, looking at self-consciousness in a much more careful and fine-grained manner, then we might also arrive at a new answer to your original question: What a "first-person perspective" really is.

Subjectivity is an ability, the capacity to use a new inner mode of presenting the fact that you currently know something to yourself.