When was "supporting Syrian Kurdish independence" ever on the table? This is an invented concern that betrays a misunderstanding of the most basic political philosophy and stated goals of the AANES and SDF. Strange to see in Congressional testimony. https://twitter.com/JennyCafarella/status/1384144162090479625

First, let's look at the political theory that informs the region's system, which was adopted by the Kurdish movement almost 2 decades ago. It rejects the nation-state altogether, instead highlighting decentralization & democracy at all levels of society.

https://www.freeocalan.org/wp-content/uploads/2012/09/Ocalan-Democratic-Confederalism.pdf

Next, let's look at constitutional documents. In 2014, when the 3 cantons that formed the predominantly Kurdish heart of what's now the AANES project first declared autonomy, they did not call for a state, but for a federal, multiethnic & democratic Syria.
https://rojavainformationcenter.com/storage/2019/12/2014-Social-Contract-of-the-Autonomous-Regions-of-Afrin-Jazeera-and-Kobane.pdf

The 2016 Social Contract condemned the "tyrannical nation-state regime" and promoted "democratic federalism" as a solution for the future of Syria. Again, there is no mention of the creation of any new state for any one ethnicity. 
https://rojavainformationcenter.com/storage/2019/12/2016-Social-Contract-of-the-Democratic-Federation-of-Northern-Syria.pdf

The 2018/19 Social Contract, once again, recognizes the existing borders of Syria while calling for federalism and pluralism internally. See the Syrian Democratic Council's explanation of it here: https://www.syriandemocraticcouncil.us/1418-2/ 
And this paragraph from the Social Contract itself:

If anything, conditions imposed by outside actors—impasses in talks with the central gov't, aggression from the mainstream "opposition" against SDF territory, failures at Geneva, etc.—are making the AANES goal of a federal, pluralist, and democratic Syria harder to achieve.

Pretending that the US has given AANES too much political engagement rather than too little, that the AANES is or seeks to be a "Kurdish nation-state," and that this is the source of problems in resolving Syria's conflict suggests that you don't know the region. End of story.