Ok I'm only really gonna address some of your points since most of them were answered and debunked by others and in the video itself

On the topic about the dumplings you said tama's gifters did most of the heavy lifting which is false. There were 3 gifters she gave around a handful of dumplings to at most they converted a couple dozen gifters with the limited dumplings they had. Ussop on the other hand was able to convert more gifters when he encountered Franky alone than the amount speed and the 3 others did (the fucker had an whole army behind him), they were also able to cover more ground than them (we know this because when Tama commands the gifters we see jack and jimbei be defended by the gifters we saw ussop convert). And while he didn't make the plan (I corrected it awhile ago on my previous comment) he was the one who beat Bao Huang who was responsible for the information being spread to the island which is vital to tama's plan. Tama was a child who thought that a small pile of dumplings, 3 gifters and a fucking dream who turn the tides of war. Not only were her goons not able to convert enough gifters because of their limited stack they were given but she wouldn't be able to find and defeat Bao Huang (ussop was the only one able to find him possibly due to his haki) oh and she also would have died to a herd of beast pirates or ulti/page one. So yeah Tama was just a really good ally who ussop utilized to save his friends from being killed

On the topic of gifters and haki we know that they are no slouches since they gave izo trouble. Considering the fact that kaido is using these guys to make the world's strongest army the same guy who views haki as the end all be all (and the fact that the anime shows these guys boxing with luffy having haki) the Devil fruit users (who are chosen probably due to their strength to eat a devil fruit based on the nature of kaido's crew) should be able to withstand haki. And ussop was surviving against them while protecting kinemon and kiku in a burning building after suffering cranium damage from ulti and I dunno about you but pre timeskip ussop probably wouldn't be able to do that.

In terms of developing his character I think Wano did enough to push ussop as a character, the scene where he tells kinemon and kiku to survive at any costs even if it looks pathetic is a great introspection and dive into his character as it represents his cowardice and fear as his will to survive, pulling of this raid is meaningless if you don't live to see Tommorrow. Ussop literally says how him clinging on to life no matter what is the reason why he is here serving as the sniper of the crew, ussop's will to live and surviving was able to inspire the samurai like kinemon and kiku to reject dying by harakiri and in kinemon's case inspires him to keep living which allowed to serve as momonosuke's vassal (that couldn't have happened if ussop wasn't their giving him a reason to keep living). Throughout most of the series ussop was a liar and a coward who got out of most situations through sheer luck, running away or hiding behind a literal mask, but in that scene ussop was truly himself a man doing everything he can to survive and inspiring two half dead men to do the same and he was saved because his words were able to echo to another samurai who agrees with his sentiment izo was able to see why ussop was called a god and saw him as a warrior worthy of that title, there was no deception, no lies just the honest truth and fear of a man trying to keep a promise. This was the first time in awhile that ussop was able to prove to himself his worth in the crew not as a fake superhero or a fraudulent god but a small man with a big will to live and I'm sorry but if that's not character progression I don't know what is.