Liquidity in Cross-Border Crypto Payments - Experiences?

We're currently re-evaluating our crypto payment rail, specifically concerning liquidity provision for various altcoins in cross-border settlements. Finding a provider that offers genuine, deep liquidity for anything beyond $BTC and $ETH without significant slippage or opaque spreads has been a consistent challenge. Has anyone found a solution that maintains competitive FX rates and tight spreads when converting less common crypto assets to fiat across multiple corridors, particularly outside of major USD/EUR pairings? It's becoming increasingly difficult to balance transaction costs with execution efficiency.