According to the webpage of the Mitteldeutscher Rundfunk of September 16th, 2023 there are about 203.640 male Ukrainians between 18 and 60 who therefore could be called up to serve.
Germany will not sent them back and they could only be returned by force if Ukraine would open criminal proceedings against them (and then it must be not one procedure against them all but it must be an individual procedure).
Since the beginning of the war you cannot claim to be a conscientious objector in Ukraine.
Links
https://www.mdr.de/nachrichten/deuts...erung-100.html