I don’t think the email alias thing comes with Mail Plus, it’s part of Proton Pass. You either need to get Unlimited which includes all of their products or pair mail plus with the paid version of Pass. There’s a chance I’m wrong because I have Unlimited and haven’t really explored it, but look into it before you commit.
Why did Proton adding a Bitcoin wallet cause you to look elsewhere? If it’s a product you’re not interested in, just don’t use it. Otherwise you’re stuck using providers that offer exactly what you want, no more and no less, which seems like such a narrow needle to thread, you’ll never find something or can’t stick with it for long.