So in OTL Nestor Makhno and his black army where an anarchist group from the Ukraine who sought to establish an anarchist system in the Ukranian Free Territory, and out of all the anarchists in the Ukraine they where probably the most successful, being defeated by the red army through trickery rather than military force. Your challenge is to instead have them succeed beyond even their own expectations and expand the anarchist free territory to include most of the OTL Ukraine (although anything west of the OTL Vinnytsia and Zhytomyr oblasts is optional).
They don't need to be totally independent and in fact my big idea for how to get this to work out would be a far less successful Red Army that is forced to rely on more localized far left movements for support allowing them to be a system within a system where the Ukraine is a separate anarchist region under nominal soviet suzerainty but full alliance and military support for the Soviets outside their borders. Also you would probably want to butterfly away Stalin given how he would want their autonomy to continue slightly less than he wants rectal cancer. Essentially I think a Soviet Union that lumbers on as an actual union of Soviets rather than a thinly veiled red army dictatorship is necessary and from there it would be possible to have the Ukraine succeed as an anarchist region within that.
They don't need to be totally independent and in fact my big idea for how to get this to work out would be a far less successful Red Army that is forced to rely on more localized far left movements for support allowing them to be a system within a system where the Ukraine is a separate anarchist region under nominal soviet suzerainty but full alliance and military support for the Soviets outside their borders. Also you would probably want to butterfly away Stalin given how he would want their autonomy to continue slightly less than he wants rectal cancer. Essentially I think a Soviet Union that lumbers on as an actual union of Soviets rather than a thinly veiled red army dictatorship is necessary and from there it would be possible to have the Ukraine succeed as an anarchist region within that.