If Amazon already had bitcoin, we'd already know by now. Since Amazon is a public company(and a company with A LOT of investors), they're required to be fully transparent on what they're doing with the company's finances.
Although I am aware of the fact that they have to fulfill reporting requirements, aren't there any conceivable ways around this? What if they found an SPOV or anything like that for the specific purpose of buying cryptocurrencies. Would there be no way for them to somehow disguise cryptocurrency related activities accounting-wise? If they invest in R&D, they also don't have to explicitly name what they are doing of course or otherwise they might have to give away important strategic details. From that angle, could there be a way to hget crypto without the public noticing?