The thing is, and we've seen this in 2020 and in the recent LA and NYC mayoral, and cali gubernatorial elections, is that black dem voters prefer the establishment option over the progressive one.
Any progressive movement needs to do a lot better job of outreach than they've been doing for the last 10 years.

Another poll cited in mid‑July reporting showed Stevens at 67% vs. El‑Sayad at 21% among Black Democratic primary voters, while El‑Sayad led among white, college‑educated, and self‑identified democratic socialists
We're just out voting the black voters, not flipping them.
If we want nation wide progressive success and a 2028 progressive presidential nominee then something will have to change.