This is something that I honestly never expected it to happen, but I am thrilled to report that I was able to connect my NYSaves 529 accounts for online access in Quicken. There were two entries when I searched for NYSaves in the financial institution list, and the first one worked for me and found my accounts.
Now, it doesn't seem to be perfect. While it recognized the target funds in the accounts and asked to add them, it shows the money in cash rather than the fund . And for some reason, I can't get the two accounts I had previously manually created to show the register view (just shows a bunch of panels), while the account I allowed Quicken to create when it found it online (because I'd just opened it) is showing the register view. I assume there is something I'm missing to view the other accounts in register view, but haven't found it.
Sadly, the earlier threads on this topic are closed, so I cannot post an update there. Curious to see how this works for others.