DeFi onramps for various other cryptocurrencies? BTC, BCH, XMR, etc.

What is the best way to convert BTC to USDC or another stablecoin without going through a KYC centralized exchange?

Similarly, what is the best way for XMR, BCH, and ADA?

I am aware of wrapped BTC, but unsure of the best way to acquire it in exchange for BTC?

Are there similar onramps to the ETH DeFi ecosystem for XMR, BCH, and ADA?