I have heard of only Omar Marmoush as a transfer rumour and he is expected to join them soon. Other than him I don't think Guardiola will make many big signings this month.
Apart from Omar Marmoush, City have also agreed deals for Victor Reis and Abdukodir Khusanov with their respective clubs. The reinforcements are very necessary for City, though i think it is Omar Marmoush that will immediately be integrated into the team.
Manchester City are 22nd in the CL league phase table, it is already impossible for them to finish in the top 8, but they must win their two remaining games to remain in the play-off places and stand a chance to quality for the RO16.
I can say that Marmoush is one of the best transfers made for this purpose. After Manchester City brings him to the team, the wing routes will be very effective. Also, with Khusanov, the defense area will be better. I think Manchester City has already started to build a better squad. They will be a dangerous team in the Premier League again next year. They will be a dangerous team in the Champions League as well. I have always trusted Guardiola's player selections.