Seeking an excellent pre-IPO tax law advisor

In a voluntary capacity, I’m hoping to help a couple friends at Anthropic find an excellent financial advisor or tax lawyer to navigate decisions around Anthropic’s recently announced stock buyback, and around the best way to donate stock. I would be hugely grateful for recommendations to people or firms that are:

• Happy with a fee-for-service payment arrangement, rather than a percentage of assets under management. I expect my friends would be willing to pay a competitive hourly rate.
• Deeply knowledgeable about pre-IPO stock option tax law, also knowledgeable about the tax law around donating appreciated stock through a DAF, and understands how these interact.
• Ideally able to take on new clients right now, though please feel free to refer anyone who only meets the first two bullets since there may be Anthropic employees in need of advice in the future.

Because this is such a nuanced and complex area, I don’t expect that generalist CPAs will be right for my friends. By default, I’m planning to get in touch with a few firms that specialize in this area and reach out to professionals on the XY Planning Network who seem like they could be a strong fit - I’d also welcome suggestions for other places to look.  

Thanks in advance; I’m hopeful that this could be an impactful match to make!