Salome, I would sent your post to Bernie if I had the connections

Not because I agree with it, and in fact I'm going to disagree with as much of it as I have time for right now, but because I see where you are coming from and I'd really like to be reassured that Sanders does, too. I'd like him to knock off the establishment talk, or at least limit it to the objects of his ire. I believe he genuinely does not believe every member or contributor to the party is part of the problem, but he may be too tone deaf to recognize that that's how he is received, by some, probably many, people.
When he talks of "the establishment", I believe he is too absorbed in top-down thinking. Me, too. People at congressional and senate level, party leadership, and I mean the very top, mainstream news organizations. And not even all of them, or the people in them. He's talking about people taking money from industry and PACs, or representing industry or PACs. He has a cynical (and I'd say realistic) view of how well a representative, or a media pundit, can represent or even understand what the people want when they are incentivized to do otherwise. I encourage you to look up "corruption is legal in america" on youtube and think very seriously about that stupid graph and what it means.
I'm going to give you just two examples of how Sanders and his supporters experience the Democratic party, in lieu of quoting some piece of your post and responding to it. Because I'm in a big damned hurry...
Obviously Sanders had problems with DWS. Her replacement? Also problematic. Not really his business, but recognize the circumstance. Both the party establishment and Bernie's supporters kinda both supported Keith Ellison as party chair. He could have been a non-contentious choice. But that wasn't good enough for Obama. He asked Perez to run, and since he was Obama's choice, of course he won. It was an
unnecessary stick in the eye of Bernie's supporters.
"They're not Democrats"
After 2016 there were two competing movements among Sanders supporters. Demexit: abandon the Democratic party and help it die, and Dementer: join the Democratic party and participate to make it more progressive. The latter won, I think. I joined my state party. In California the effort was so successful that they thought they would have the numbers (and support from lots of party insiders and elected officials) to elect a progressive black woman as state party chair. But they learned that there are superdelegates at the state level, too, and a voting mechanism that can be hidden when it is convenient. So, a pharmaceutical lobbyist won that chair.
How's that for a stick in the eye? California was making moves toward M4AllOfCalifornia. With the party chair a pharma "consultant" and lobbyist, and Pelosi reassuring the industry that nothing will come of M4A, Dementer fell out of favor in California. No clue if it's even still a thing.
More to come if I have time.