You can use a live OS with pre-installed Electrum on an air-gapped PC to create your seed too. After the generation is complete you can wipe the disk if you're paranoid about it. Anything can be compromised but that's why verifying files, airgap pc, etc exist.
You're right and that approach you mentioned is perfectly fine and recommended for most people who cares about security and safety. However, I don't think it is suitable for true paranoids. By using air-gapped computer and other things you still rely on software in terms of generating of randomness and other calculations. Using of open-source software might help so that you can check and read code for yourself, but this requires additional coding skills. I also don't recommend manual hashing because it is too complicated for unexperienced users and can make things even worse.