In the US anyone who transfers crypto may fall under money transmitter license requirements. It is easy to get into trouble for running afoul of this and is one reason localbitcoins doesn't exist anymore. Also I'm not sure how you would confirm destruction of any item without a large chain of trust of the actors. Crypto is all about Zero Trust.  Also easy transferring crypt to fiat without going through an exchange or other methods that by law must comply with Anti Money Laundering / Anti Terrorism laws is going to be faught against by every government.  Binance tried to ignore that, they paid billions in fines and CZ is doing time.

In effect the proposed solution takes a few centralized exchanges for the fiat / crypto exchanges to a slightly larger centralized network.

Of course it is always easier to point out problems than to come up with solutions.  I do like the out of the box proposal. Keep thinking of new options, if you can solve the problem it may be very lucrative to you.