They should be deporting the Ukrainians in Poland breaking the law.
That's not enough to staff even a company-size formation. Let alone a battalion or a brigade.
The initial discussion, was that Poland could train several brigade sized units.
That's what Sikorsky is gently poking fun at, when he says "on the Polish side we have done everything required, but the volunteers still fail to materialize."
You need to start sending all the Ukrainian men that Polish police can get their hands on, in order to provide real muscle to Zelensky.
With Polish training (at least several months, and Not 3 weeks like in Ukraine) and weaponry, the mobilized could become a lethal force on the battlefield in Ukraine.
However, I'm afraid that your Dutch, French, and German allies will throw a fit if Poland is seen loading train cars with Ukrainian deserters.
All of Ukraine, managed to supply only 3,500 men from their prisons when they finally made the decision to copy Russia (in Russia, the number was 40,000). The reason Ukraine mustered so few is because they refused to recruit rapists and murderers, and only drew on people convicted of violent assault, burglary, and fraud.
So I fail to see how Ukrainian criminals in Poland could supply more than 50 men.