"Germany promoted absolute extermination of Poles" as did Soviets.
With respect I don't think is quite true.
Germany's plan for Poles was to use the Polish nation as a "pool" of slave labourers not "absolute extermination" (unless it was Polish Jews) hence the several million Poles deported to the Reich as forced workers and not sent to "extermination" camps. Plus the majority of Poles who were not deproted as forced labourers during the Nazi occupation were not being singled out for extermination. Extermination through work did not apply to most Polish forced labourers but mainly against Polish Jews.....or am I mistaken?
The Soviets also did not promote "absolute extermination" of Poles either but the removal of all those it thought likley to resist the Sovietisation of the occupied Eastern terittories hence the mass deportation of those Poles (and their families) considered by Soviets as 'enemies of the state' to slave labour camps and settlements. The Soviet murder of Polish POWs was to rid the Polish nation of its leadership ie. Officers. Other ranks were sent to slave labour camps but this treatment of Polish deportees was no different to earlier deporations by the Stalinist regime of 'enemies of the state' from the Soviet republics and occupied territories, and not a specific policy directed against Poles per se.