Couple of issues here that are separate
If a donor donates money, then in QB you should have a bank type account named for the brokerage and you show a deposit in that amount as donation income.
If a donor donates stock, then you should have an asset account named for the stock part of the brokerage and you enter a deposit in the donated stock asset account as donation income. This can be dicey, you need to talk to the brokerage about how they establish donated stock cost, since they now report that to the IRS when a sale is made.
if you get dividends paid to the brokerage account from the stocks you hold, then that is a deposit to the brokerage banking account in QB as dividend income
If you sell a stock, then you reduce the brokerage asset value by the cost of what was sold, and that cost is a deposit to the brokerage bank account. Then the excess amount received over cost, is a deposit in the brokerage bank account as income.
No there is no way to see actual stock holdings in QB, QB is just not set up to track investments in stocks at all.
Best option there is to rely on the brokerage holdings listing and or, use quicken or a spreadsheet.