i dont see the need to commit any reserves at this point for the russians. if there were reserves commited, i imagine those are simply reserve battalion of a brigade or something. at the operational level, i cant see russia committing reserves unless their last or second last line of defense is breached, or the commander sees an opening to exploit against the attackers.That's a significant commitment.
At this point, a commitment of RuAF reserves is probably justified, but it's only been 2 weeks or so. There is plenty of ground to give, a good opportunity will likely present itself at some point.
on the ukrainian side, i have been hearing some people suggesting that they have committed their second echelon, because the units that initiated the attack are different from the ones that have captured some of the towns recently. rumor has it that NATO countries were not happy seeing their equipment all over the internet in pieces, and ukraine had to pull back a bit and commit non-western equipped units instead. my suspicion is that these units were tasked to slug it out with the russians in urban areas anyways, while the western-equipped units were supposed to steamroll the russian defense out in the open. so to use the former to capture small villages actually makes sense.