I wouldn't know; I usually stay away from youtubers that mass produce videos, that does little else but confirm and justify their own preexisting bias, especially when it is hate-driven.
If you want an informative and unbiased opinion, your best option is to seek out those youtubers, that were mostly unbiased before the show was released (they exist).
Someone reminded me that in his letters, Tolkien mentioned that early Second Age Sauron had a genuine "good" period where he was well-intended and trying to turn his back on his evil ways (but couldn't quite find the humility to truly achieve repentance).
And that I think is the missing piece to make Sauron-Halbrand fall together: Halbrand's whole remorseful act and desire to get away from past evil being *genuine*. Then he hasn't successfully deceived Galadriel, his being in the middle of the sea is not a cunning plan, his stumbling on Galadriel is not insane good luck but the worst of bad luck, his warning her about his own nature is not some weird double-bluff but the genuine truth, and Gil-Galad's "her own obsession might awake the evil she's seeking" goes from head-in-the-sand management to entirely accurate prescience, and Adar's anger at the name stops being jealousy or rivalry and fits perfectly as the reaction of someone who feels *betrayed*.
Well, great villains never perceive themselves as 'evil'; Sauron would fit into that category. Sauron's end goal for Middle-earth is order, obedience and industry. To achieve that, he needs to cleanse it for 'unwanted elements' first. There's a synergy being established between Halbrand and Galadriel, I feel. They are both outcasts from their kin, from both their own design and external reasons. And yeah, I don't see a bright future for Halbrand either.
I think Adar has been assigned by Sauron personally to establish his reign in Mordor. I believe Adar needs the broken sword hilt for this; perhaps he needs to perform a ritual with it, as depicted on the mural we saw - a sacrifice to cause Mount Doom to darken Mordor and make it livable for orcs perhaps. I still favor the pet theory that Sauron is already in play; the showrunners are just keeping him off screen until the right moment for the reveal.
I have a hunch about Adar's line about 'not being a God - yet'; it connects to the above.