I'm hoping you're right.
What I could imagine is that he just wants to burn through the prisoners since if they don't make it back, that's less prison costs. So even if he has reserve troops available, he'd rather use prisoners first.
If that was his plan he should have sent them in first before he lost 470,000 registered soldiers. This is a desperation move, and if not that, then it is one of absolutely colossal foolishness. Neither is a good look for Putin.
I think the crisis moment for Ukraine has passed mostly. The threat of a breakthrough from a couple of months ago is not gone, but stalled long enough to shore up the defensive lines and have ammunition and supplies delivered from the west (and let's be honest here, that is still for 90% coming from the US). The strategy for Ukraine should now be to hold line and hit the supply lines.
The sanctions that were implemented take time to really bite and you start seeing the results of these more and more.
One thing I think Ukraine should do is start recruiting mercenaries from Nepal and other places where Russia is recruiting. Since they're not (or rather "probably would not") be thrown in the meat grinder, I think that after some time they can dry up those sources too, while at the same time addresing some of their own manpower issues.