Hi @bearfly,
The WalletConnect explorer dApp is using the CASA chain ID standard , which we do not support. The vast majority of functional Solana dApps we support use the native representation.
So, if you find a real Solana dApp with a devnet interface, you can connect it to your Sandbox workspace via the desktop connector.
Lastly, Fireblocks does not have an official demo dApp.
Can you share a screenshot of where you are seeing the accountId?