In summary, does Avast's Free Firewall provide greater protection than that of Windows 10 and / or 11?
I'm pretty sure nobody can answer that. Because their replies would be biased.
If there was a list of all specific differences between Avast Firewall and Windows Firewall, then we could at least try to compare.
In any case, consider this:
How many users there are using Windows, and how many reports for bugs and vulnerabilities over the years Microsoft would get and fix?
A lot. (And most people just keep Windows Firewall).
And compare that userbase number to Avast Firewall userbase number (not Avast, but actually this Avast Firewall itself) and a possible amount of reports. Just a very different order of magnitude.
So from the "bug and vulnerabilities" standpoint, Windows Firewall must still be more polished and safe. And besides, judging by earlier comments in this thread, Avast Firewall, even in the paid version, was oversimplified and it currently lacks some control and functionality that Windows Firewall has.