I'm not sure it would even make much sense for them to work at a FAANG. Running a small entrepreneurial business is so different from succeeding in a large corporation. In one you need to be a master of everything from marketing through to development, in the other you are going to need to be highly specialised to merit a large income.
My guess is he wouldn't want to work in a FAANG and they wouldn't want to hire him.
I've worked for Amazon and all I had to do is getting permissions from teams and then do some config changes (or similar level programming) in their software.
Needless to say year-by-year I forgot everything I've learned before. My CV might got a boost, but my skillset decreased a lot. Only thing what I've learned is politics and how to push and decorate an empty promo doc.
I was a braindead when I finally got my stocks.
So went back to the startup word, where I could thrive.
The average lifespan was like 1 year there, most people did not even wait for the stock so basically worked cheap for amazon.
My guess is he wouldn't want to work in a FAANG and they wouldn't want to hire him.