The question in that thread is about Zcash. I can't say anything about Zcash - I've never used it. But I can give some advice regarding Bitcoin, so I'll answer here.
A great way is buying on Robosats. Their community prioritizes privacy. A specific plus is that you receive Bitcoin over the Lightning Network, where no one can track their history.
An alternative is LNP2PBOT. It's useful if you don't have any Bitcoin yet. On Robosats, you need a security deposit to make a purchase, and that deposit can only be made in Bitcoin.
So, LNP2PBOT is a great way for your first purchase, and Robosats for subsequent ones.