I keep thinking I've got a solution, and then keep realizing that it doesn't actually do what you asked for.
This is a bit of a weird use case, though. Could you explain what you're trying to do at a higher level, such that these restrictions are necessary?
there is no situation where this would be useful...
It cannot be done within bitcoin, as txscripts are not dependent on the blockchain, or any other external state for that matter. txscripts only decides whatever a transaction is approved by the owner(s).
Yes, but you can use txscripts to make transactions dependent on each other using cryptographic techniques (e.g. CoinSwap, where hashes of secrets are used to make one transaction contingent on another).
The problem here is that I'm not familiar with any cryptographic techniques for
simultaneously revealing information.