The Co-op (coop) experience is antagonistic to playing Co-op

PoE2 says that it is a co-op game. The problem is that playing co-op in the current version of EA feels like you are being punished for playing co-op.
The bosses feel like they don't understand how to exist with two idiots punching them, so their lead up to attack doesn't operate how it does in the solo experience. I've been nuked by an attack that was telegraphed to be towards the other player and just went at me. This happens routinely and I don't know if it's the mechanics of bosses or just that the game throws a fit at co-op, but it turns boss fights you understand into chaos where you are just tuck and rolling constantly because who knows if the boss is gonna drop a boulder on you or your cohort. I can't imagine what happens if you play in a group of three (can you play in a group of three? Man, I need to make a second friend so we can see)
So bosses are a tad wonky.
Rewards.
All orbs and "material" should be per player present. I know that this would jack up the economy, but I also don't like having to go, ok, who's turn is it on exalted orbs. And lord help you if you play with someone who hoovers everything up.
The main issue though is the end game. (I'm not really impressed with the experience, but it is what it is) The Trials and the map (I'm dumb, I don't know what you are calling it, the Atlas? I don't know. Unimportant). The Trials and Map can only be accessed/done by the party leader, which is fine, but slightly tedious. The problem, especially in the map part, is that if they die, they can't be brought back and have to watch you slowly meander big ass locations because they got vaporized by everything. The solution here is to have a total revives system. 5 or 6 or whatever you give us. It's just a group deaths thing.

Guy I play with really likes ARPGs and was enjoying the game (from what he's expressed) and after we got nuked by an infinitely spawning enemy that kept slapping us and following us, we happened upon that dude on a land platform that has jerks raining arrows down and he died because infinite spawn plus all the dawgs plus the boss. He died and I ran away to get a little space and that infinite spawn enemy just kept coming no matter how many times he died. Guy said he is done with the game, at least for right now, because if either of us die in the end game, all you are doing is looking at your phone and talking. And having me fight the same bosses we already fought in the story is dumb. It feels lazy.

So a simple "solution" here would be team deaths when playing in co-op and fixing whatever causes the bosses to spaz out.

PoE 1 already has and PoE 2 is going to have Link skills which link you to your friend so you both get buffs. The downside is that similar to Battle Royale 2 if one of you dies, you both do.

I think team revives would be a better system, but I'm dumb, what do I know.

That would trivialize the game too much. Loot drops are already better the bigger your party is so its always beneficial to Party up in the game.
Your other complaints are common problems in other co-op games too. Cuphead a great example, that game is actually way harder in co-op because the bosses switch targets and become unpredictable. If you mod your Elden Ring and try to co-op it with your friend, you will run into the same problem where boss suddenly switches targets and nukes your mage friend out of nowhere before he has time to react.

think yes 1 chance to revive per map and lose all portal so no more chance
its a penalty but u can have a fail in a teams of 3-4 player