What does the tooling look like for developers when building a dapp using QuickNode?

It varies widely. I did customer support for us for quite some time, and it was everything from just a frontend library like Ethers to their own homegrown rolled HTTP wrapper that they make their own stuff with. There's starting to be quite a few of these sort of abstracted wrappers around what was previously just interacting with the blockchain. So you would see Ethers. You could see thirdweb now as one of these abstracted ones. Web3.js was the very first one.

Then in every language, there's a whole gradient of very raw to higher level— Web3.py., Ethereum.rb., Web3j and in each one of these, you can see some custom implementation and some forks. That's the latter part of their tech stack. Once you're fully deployed and live on Mainnet, that's probably what you'll see.

But then, there are the earlier parts. You've got your Testnet stuff and when you're in it, you're thinking of dealing with things like Hardhat, or OpenZeppelin, or Ganache.Those are sometimes simulating or forking Testnet. 

There's Tenderly, which is actually a paid service. It's not even just an open source dev tool, but Tenderly will give you stack traces like Sentry. 

So, the tooling is immense, and it's still not good enough. On top of all of that, you do need to worry about where your files are going to be hosted. Are they on arweave? Are they on IPFS? Are you just hosting on a centralized server? If so, are you still at least delegating most of the files serving to the IPFS or the arweave?