[lxgr]

I don't have access to, nor a need for, the 40W charger, yet I'll continue speculating about it (which is why I prefixed my comments with "I could see", "it could", and "I suspect"), thank you very much.

Mainly, I'm trying to understand why AVS is supported by both the phone and the adapter if supposedly it makes effectively no difference.

It could be as simple as being a requirement for PD 3.2 wall adapters, of course, but that raises the question for why it's required as well, if it's supposedly that irrelevant.

[coder543]

There is nothing to speculate about here, other than to create confusion for others. The physics is immensely clear. AVS is not needed here, and OP can save money by buying whatever is the cheapest option that provides >40W.

Since I have shown through basic math that it isn’t related to the ability to charge the phone any faster, that possibility is obviously eliminated.

AVS is likely supported because there’s no reason not to support it. It is part of the newer USB-C PD specs, which Apple wants to support, and it continues to iteratively refine the energy efficiency of the charging process, which matters a small amount at a scale of billions of devices, but doesn’t matter at all for a single individual’s purchasing decision.

[lxgr]

Sorry, I wasn't aware this was a tech purchasing recommendation site instead of a discussion forum for hackers ;)