As long as we are dreaming, let's look at the inverse thing.

Recieve-replace.

You lightning invoice fiat in your EDC wallet (see my other post, is there a better term for this btw), receive, autotransfer to exchange, and autochange to fiat in the amount expected, ideally guaranteed by exchange if completed in short amount of time.

There are products like bitpay that already do this, but it locks you into bitpay.

You want a generic thing that lets you hook up any EDC wallet to any exchange that supports the protocol, so there is competition.

Well, the problem with this is

1, low demand, as in the spend case 2, exchange and banks and everything else outside the bitcoin ecosystem is incentivized to maximize inconvenience and "uniqueness" to promote lockin.

Doesn't mean it's not a good idea though.