The insight journey into the nature of mind can feel like a process of realising seemingly deeper and deeper fundamental identities, as your consciousness becomes more transparent to itself; eventually opening up your energy field, until there is no centre and no sense of solidity to experience.
Then the existential question of what ultimately are you becomes moot; and instead, understanding the nature of mind becomes less of a 'what is' question (to be answered as or by any thing) and more of an open ended, evolving exploration as life reveals itself.