Actually the big news that has been reported is already a big proof that the Tesla really buys bitcoin on the blockchain and if you are really curious on how they buy it or on how transaction they buy it then probably it would be really good if Elon Musk will share on how they do it, if they do it by single transaction or multi transaction. I am pretty sure that it will be a entertaining topic if they share us on how they do it and I believe that many people are also interested on this.
maybe what you say is something that can make learning for us how a very large company like Tesla buys bitcoin, because obviously with a large value it will certainly involve a lot of institutions and is something that doesn't make sense to do in one transaction because it can't possibly happen. . but it is something very interesting too if it can be known.
but because this is a corporate institution, clearly requires policies from others and cannot be monopolized by @elonmusk, maybe this is what no one can and cannot possibly do to find out. policy is to be done together, so don't expect the word to get out.