This is an entirely unbaked idea that really only follows the lore as we have seen it in the show and in general for how shows and story structure tend to work...
But with season 3 Haladriel what I would do is definitely have more mind palace shenanigans but have them be more visceral than dream like.
Galadriel on her journey to become The Lady of Light? To get to where she can completely block out Sauron?
I would have this season where she gets as close to the darkness as she will, Galadriel's dark arc. With the stab of Morgoth's crown, I can't imagine there isn't gonna be some fun bound or mind palace shenanigans.
In Act 3 of a supposed 5 act story, this would be were the descent reaches it's depth in the overall story (and I am of the belief that the story is mostly Sauron x Galadriel, people can disagree but idc). Galadriel has been on a steady decline and this is where she'll truly hit rock bottom.
It starts out in Galadriel's mind as a way to discern where Sauron is and his plans but also that secret part of her that uses it as an excuse on why she can't stay away because we know she has to fight to deny him and with the Morgoth STD I think could chisle away are her willpower and make her more susceptible at deceiving herself ala a parallel with Sauron. (Having her fight with her pull to Sauron end in season 2 is so BORING.) And well, Sauron is Sauron and he can't help but play with his bby lady of light. Maybe he teaches her things about how to deal with the bound thing with Morgoths crown or the mind palace itself.
Anyways, lines are crossed, motivations are blurred and Galadriel actually begins to fall to the darkness but still not quite but she is being seduced (give me my fucking kiss and all the they are fucking metaphors Amazon/Tolkien estate).
This would have their most toxic, messy, dramatic interactions as lines are blurry as FUCK and boundaries are crossed.
But Galadriel being her boss ass self comes back, maybe on her own, maybe through Elrond and then from there we would go into act 4 with the momentum of the Saurondriel story where Galadriel can and IS actively resisting Sauron with what he taught her and coming into her own as the Lady of Light where he is defeated in act 5.
Like I said, half baked, all over the place, not fully fleshed out but yah. Would def need some polish and work but that's about how I would do it. Have Galadriel reach a low point but finishes the season firmly on top in the Saurondriel ship and leaves Sauron shaken like season 2 Galadriel as he begins HIS descent and maybe that leads to him fucking up in Numenor or something.
“identify what it is that your opponent most fears.” not to exploit it, but as “a means of mastering it, so that you can master them.”