I'm dumb so don't listen to me but doesn't the brain hallucinate when confronted with like a lack of stimuli? Thinking of deprivation tanks and isolation experiments and such.

People placed in isolation tanks for long periods have reported that consciousness seemed to become more vivid when deprived of external stimuli but that it was increasingly less grounded. Without real world input consciousness does not shut down it constructs its own simulated input.

We haven’t even figured out what qualifies as consciousness and what doesn’t. Studying something that’s not clearly defined won’t be easy. Also, we might be thinking about it in the wrong way, asking the wrong questions and using the wrong words.

Basically you're asking if you are a brain in a jar can you still think or have a sense of self

Well i read somewhere that in absence of signals the brain would just gradually become more sensitive until it even responds to things that aren't there, basically hallucinating.

Well, you asked a question that doesn't have a definitive answer.

However, nerve endings aren't the end-all be-all of the sensorium. The brain has activity, even when cut off from stimulation via the senses.

We aren't reliant on our bodies for "self*, in other words.

If you consider dreaming consciousness then no, since thee's no synapses being triggered. This is the part where some expert in the field slaps the confidence out of my mouth

In general, nature gets rid of stuff that is energy expensive and it doesn’t need.

No sensory means no reason to think so yeah probably.

Yes

We probably can't know, and certainly don't know.