* The wallet is enabled by default.
* The new tab page shows crypto ads by default. I couldn't figure out how to opt-out of these despite a couple of minutes in the "customize dashboard" menu. I know the option exists, but it's well-hidden.
* The BAT rewards icon is enabled by default, as well as the new tab card, as well as injected tip buttons on Github, Reddit, and Twitter.
* BAT rewards itself is not enabled by default, but there are no less than 3 distinct notifications asking me to enable it.
* Brave news is not enabled, but again there are multiple requests to enable it hidden throughout various menus. It's also not clear how Brave news interacts with Brave rewards. If I only enable news, do I still get the in-feed ads without the reward sharing, or is the news feed ad-free, or will only certain ad channels be shown?
So no, the crypto stuff is not opt-in. It's mostly opt-out with the BAT rewards program specifically being opt-in.
Most people referring to the "crypto stuff" are talking about that program where you get an ad every once in a while and get some crypto for viewing it. Certainly not a fan of it myself and would not use (let alone recommend) Brave, if it was imposed.
Now I have no problem with their search engine if it is good. Alternatives are definitely needed. If they start pushing their token through it or weighing results based on the token in some way I might think again.
Customize->Background image. Has a total of two switches. One for background images at all, the other for sponsored background images. Turn the second one off.
Not since the early 2000s when browsers were infested with random toolbars have I seen so much shady spam in a web browser.