I stayed away from cryptocurrency when DeFi and Web3 and NFTs were everywhere, but I've started paying with BTC where I can, so I don't have to deal with banking apps, and to stick it to puritanical payment processors, after the Steam/Itch debacle.

Know Your Customer is acceptable. Nanny Your Customer is not.

Monero is the cryptocurrency everyone uses for this. The userbase and community is completely separate from the Web3 NFT dog-coin crowd (unlike Bitcoin).

There's also systems like PaySafeCard, which is accepted by Steam.

I'm really interested in Monero. I feel kinda nervous about using it, though, since even though everything I'm buying is legal, it feels like I'd be calling a lot of attention, and I want to make sure I'm buying and exchanging it in legal (if private) ways.

Using Monero is not much different from using Bitcoin. It's actually safer than Bitcoin in this regard, as you can't accidentally receive coins that are "tainted" by what previous owners did with them.

Know Your Customer is not acceptable at all. It is the financial arm of warrantless global mass surveillance. The government got the private sector to do all the surveilance for them.