This was a mystery for me for the longest time, because it was so far out of my comfort zone I couldn't conceive of it working. Here's the whole secret, ready for it? Email people and ask them for what you want. There are a range of possible outcomes to this. Them giving it to you is quite likely, particularly when you describe it as in their interests. Them sending out a company wide letter saying that you are a bozo who had the unmitigated temerity to send an email to the CEO of a company you did not work at is also possible, but that is extraordinarily unlikely to happen.

I need a button for this when I go to conferences, since some people (not too dissimilar to a younger me) think that it is an imposition to come up and introduce themselves at an event I am explicitly attending to meet people. I have had folks apologize for introducing themselves. That's crazy. I run a wee little spec of a company and transparently love talking to people. In the event that I'm not interested, I'll just mail back a sentence to that effect or (more likely) just put it on my todo list and forget about it.

There are many, many, many tech CEOs who are that open or more. Heck, Steve freaking Jobs famously answers mails sent by individual Apple customers. Getting an interview with a startup founder is not difficult. Just ask.