The problem is that these peoples are structurally between the Slavic rock and the Turkic hard place. To elaborate, they lack an agricultural base to compete demographically with Slavic states and they do not, for the most part, inhabit the steppe, with the military edge that steppe nomadic lifestyle brings.
A deep boreal forest crop (something analogous to North American wild rice perhaps?) or domesticate (moose seems the best bet) would help.
You could have a trading proto-state centered on the Northern Dvina river basin (Bjarmaland). It sort of existed IOTL but was assimilated by Novgorod -demographic imbalance I think.
Further Northeast, polities in the region called Jugra existed until ca. 1500 in the general area of modern Komi Republic. The local peoples converted to Orthodoxy and adopted Cyrillic script, but again, demographic imbalance with Russians led to eventual absorption.
Perhaps you could have a situation where a larger section of the Kazan' Tatars assimilate linguistically into the Volga Finnic groups such as Mari, Meshchera and Muromians, leading to a Finnic-speaking *Kazan' Khanate which in turn spreads its dominant Finnic language. This would be the reverse of the OTL situation where at least part of the Finnic Meshchera (already partly subjects to various Russian principlities) assimilated into a Tatar linguistic identity as the Misher people of the Kasimov Christian Khanate.