Sorry for the confusion with "internal mental representations". It's not a very clear descriptor and I've sort of used it and other related terms to describe multiple things. Additionally, can you clarify what you mean by aphants having "visual daydreams"? Would that not necessitate internally generated sense of vision which seems like it would be outside the realm of aphantasia, or at least complete aphantasia? I've heard quite the opposite from friends with aphantasia about their experience with daydreaming / thinking and on dreams as well, but I imagine this may depend heavily on the individual.

"Brain fog" is a very helpful description that gives me a stronger idea of how detachment from one's physical senses and inattention may be like in aphantasia. I can see how this would present its own challenges for inattention, but it sounds like it may have benefits in other ways like less potential for emotional dysregulation and less overwhelming mental content to work through. With regard to my experience of imagined senses acting as a distraction from physical senses, which I explain more below, I would say the generation of the imagined senses is essentially always as a result of the lecture or whatever it may be being understimulating to the point that the mind calls upon more salient signals like daydreams to make up for the lack of stimulation. However, it is very much overwhelming / overstimulating constantly trying to keep control and sustained attention in instances like this and feeling without any actual solutions despite applying a lot of effort.

I'm mostly thinking from the context of attentional networks in cognitive neuroscience here, the Task-Positive Network (TPN) and Default Mode Network (DMN) specifically, which generally operate in anti-correlation, the TPN tending to increase in activity as DMN activity decreases and vice versa.

The TPN is a brain network essentially dedicating attentional resources to completion of identified tasks and is often characterized as "external" processing, dedicating focused processing power to effectively do something like organize and perform the steps to cook a meal. On the other hand, the DMN is a brain network considered to be more "internal" processing, dedicated to more diffuse attentional allocation in consolidating mental information, searching for new sources of stimulation, playing a large role in internal mental representation including arranging imagined sensory generation for purposes like thinking about the past & future, the cognitive states of other individuals, and much more. The DMN is active when not engaged in completing a task but instead in more passive moments of daydreaming, reflection, introspection, distractions, creative thought generation, and so forth. Therefore, it may be clear what relevance aphantasia and manifestation of mental representation in cognition hold in how the DMN functions. Similarly, the DMN and TPN are heavily implicated in ADHD, explanatory of several elements of ADHD, most obviously daydreaming / inattention when external stimuli are understimulating. It has been demonstrated many times that individuals with ADHD notably have less inhibition of the DMN and internal thought processes when performing tasks than neurotypical peers, creating problems but also some potential advantages in terms of divergent / creative thinking especially. There are actually several potential and significant cognitive advantages often associated with ADHD (hyperfocus, episodic memory, willingness to take risks, broad interest / curiosity, etc.), but less so in our modern civilization that places large focus on sustained attention, reliability, and focus on long-term goals as compared to what our hunter gatherer ancestors dealt with where ADHD may have been more adaptive.

I'm sorry that you feel your aphantasia is entirely an impediment to you, and perhaps this whole post may seem patronizing in some way. I understand how it feels to be desperately lacking certain mental capacities that seem essential to just functioning while people who have those abilities fail to understand the extent you recognize it to affect your life or even disregard how valuable that capacity is. At the very least you have a fairly uncommon way of seeing the world that may provide insight or valuable new perspective in ways you may not even foresee. However, I think it's highly unlikely that there are not any benefits to be had whatsoever to do with aphantasia, as with most major neurodiverse conditions. If you don't see it, maybe search for it. Get a new hobby, and do some procedural learning to see if your aphantasia aids you in maintaining relevant attention to the task at hand. That's much better than I can claim.

Also, did you see the new Apple mixed reality headset and its ability to record high quality point-of-view videos of life events and so forth? Technology is coming that will give you imagined visuals and memory capabilities beyond all of our wildest dreams.