diamondABI hardhat task has been created to create an ABI file from all the facets used in a diamond.
diamondABI hardhat task code is here: https://github.com/aavegotchi/aavegotchi-contracts/blob/master/tasks/generateDiamondABI.js
The diamondABI hardhat task is executed on the command like this:
npx hardhat diamondABI
The resulting ABI file is generated at