This has huge potential.
I see that the focus is really on async context right now - but the possibilities with something like this for sync transactions are really exciting. E.g. have code react to a governor limit exception (such as undoing an API request made during the transaction) - or have much more elegant logic around ensuring transaction rollbacks in case of exceptions with the option of further DML.
There are many times working on the platform I'd have killed for something like this - really excited to see where this goes.
@Charles Troster hear you. This is one where slow and steady wins the race, since for sync requests we're talking about potentially doubling the resource consumption allowed per request, AND we need special handling in each use case to make sure it works as advertised.
This will be a long journey, but that's where I plan to take finalizers, albeit starting with async since it has the least material concern about resource contention.
