When it comes to privacy, monero should be your go-to solution. That's are tried and true. If you want privacy for other blockchains, I definitely recommend checking out the work going on at
incognito.org. They are working on some great solutions to add privacy in a legitimate way.
If I understand correctly this Incognito stuff is neither supporting mainnet Bitcoin nor mainnet Monero, and it has some new shitcoin centralized blockchain with worthless tokens, bridges and other crap like that.
I wouldn't call that privacy at all, especially when there are legitimate options for exchanging coins with atomic swaps or using Bisq exchange.
Talking about privacy wallets, there is one option that uses Layer 2 Bitcoin statechains, and it's called Mercury wallet.
It's far from perfect, but it's one more privacy tool and developers are actively working on improving code and implementing Lightning Network.
I think your post about incognito was a bit one-sided. You must not have gotten very far in your reading.
- Yes, it uses its own blockchain. The mainnet token of their blockchain is used mostly to pay for the fees used to create transactions or using the dex if you are using it only for privacy purposes.
- No, I don't think it directly supports mainnet bitcoin or mainnet monero, other than adding a privacy layer for its users. No, it is not centralized, there are plenty of full node operators. No, its tokens and bridges are not worthless, they add privacy to dexes on multiple blockchains.
- There is no requirement to use the token for any other purpose than that. If you do use the bridges or dex, there is usually no slippage as it's liquid. The wallet and pTokens (wrapped cryptos on their privacy chain) are equally as easy to exit back to the original mainnet as they are to enter from the mainnet.