TikTok is literally a separate entity from ByteDance. They are owned by ByteDance, but they are not the same company and operate separately. Again, you are conflating the two
which is probably harder and more complicated than just getting it from Tik Tok
Probably not harder. Keeping a multinational social media platform going seems way more complex than buying the info. Which is why the US government does it (it is also a way to skirt the constitution, BTW)