yes, Polkadot uses sr25519 (ed25519 but with schnorr signatures) and Monero uses ed25519. sr25519 is just objectively a much better signing scheme, but Polkadot is otherwise unremarkable. ed25519 is a standard choice for the extremely paranoid, as SEC (creators of secp256k1) are an arm of Certicom which is probably just fucking filled with CSIS spooks. so there are many good arguments as to why a use of Bernstein and Lange's Edwards curve should be preferred for the security and privacy conscious.