Suggesting ERC20 and ERC721 on-time off-chain approval for safer NFT trading

Just to clarify, in the subject “on-time” do you mean “one-time”?

For the context, there are a few approval related EIPs. I am also working on a general approval EIP called EIP-5453 Endorsement,
that solves general limited time approval problem. Feel free to join its discussion here