have these 'improvements' been backported to pandas now? i would expect it to close the gap over time.

Yes (mostly) is the answer. You can use arrow as a backend, and I think with v3 (recently released) it's the default.

The harder thing to overcome is that pandas has historically had a pretty "say yes to things" culture. That's probably a huge part of its success, but it means there are now about 5 ways to add a column to a dataframe.

Adding support for arrow is a really big achievement, but shrinking an oversized api is even more ambitious.