1782 map of the Russian Empire

bit.ly/3T4wMiS

‘I wonder how well the Russians actually controlled the more eastern regions

Mostly limited to what later would become the route for the trans-Siberian railway, so the most southern strip of Siberia. The construction of the railway led to an economic boom in the region, since it is rich in coal and iron. The northern parts of Siberia where very remote and had extremely low population compared to its size, so there was also no real incentive to control those regions. When the 20th century oils and gas fields where found the northern part also became more interesting, and just like a century before new cities where created due to the economic interests.

Around this time (late 1700s) it was just beginning to be the case that the Russians would use a route through the steppes and were starting to settle the steppes with farms.

But for 200+ years before that they actually didn’t have control of the steppes and anyways were more interested in using the river routes through the forest to get furs. Furs were the entire reason for the expansion to the Pacific. They also used a northern route along the Arctic up until 1700 before going entirely through the river routes.

wikipedia.org/wiki/Siberian_River_Routes

Prior to the late 1700s the Russians did not have a big advantage over the various Khanates on the Asian steppes, at least not an advantage with the small bands of cossacks that they conquered the forest belt with. I remember reading an account about the cossacks on the river routes - they would have to haul all the grains they needed east with them from the Urals because they couldn’t farm on the steppes. It was too dangerous. There was at least one settlement attempt where they tried to grow grain that got annihilated by mounted archers of some confederation or another.’