import { createPublicClient, http } from "viem";
import { mainnet } from "viem/chains";
 
const client = createPublicClient({
  chain: mainnet,
  transport: http(
    `https://mainnet.gateway.tenderly.co/${process.env.TENDERLY_NODE_ACCESS_KEY}`
  ),
});
 
 
console.log("Block Number", await client.getBlockNumber());

https://github.com/Tenderly/tenderly-examples/commit/3c74573f24680f4e59caf595361b3fc79611233b