Google X Company not giving GSUs but company stock, help needed
So today I did an interview with a graduated Google X company, the interview went quite well and I'm advancing to the in-campus interview but when we were discussing the compensation and I disclosed how much I'm making at Apple (currently $180K + 20% bonus + $450K unvested stock), the hiring manager mentioned that I would not receive GSUs (RSU from Google) but stocks from the Google X company I'm interviewing for because Alphabet policy is that once a company graduate from Google X, they give to the employees stock of that company rather than Google so they are motivated to see that company achieving their target and potentially receiving a very good future compensation.
But things get not so clear when I asked what would be the valuation of the company, the hiring manager said that this is a confidential information and they wouldn't be able to tell me even if I join the company, because since Alphabet doesn't disclose the valuation of their graduated Google X companies they can't tell that info, so basically I would have to estimate it by myself which is something that I don't understand and I also don't get how I would be able to cash those stocks in the future.
Anyone has any experience with this or can explain it better to me? I'm thinking that I'm not willing to leave my unvested Apple stocks ($450K) for stocks that I have no idea of their value or how/when I could sell them. Any help would be appreciated about how Google X stocks works for this companies that are graduated.
Current Apple TC $400K