Before I head too far down that path, is there any reason I shouldn't be able to use/import Viem as a module into my Defender action and use it in lieu of Ethers as my blockchain libary along with a Defender Relayer/Signer?
Yes you can use / import viem in your Defender actions; however, the defender-sdk only supports web3.js and ethers.js at this time for use with our relayer/signer. Feel free to raise an issue in the defender-sdk repo requesting support for viem