What are the alternatives of Hajj and Umrah (to please Allah) who can't afford it?
Anything you would do with good intentions and in the way prescribed in Quran and Sunnah, either it is from the rights of Allah (Huqooq-ullah) or from the rights of his servants (Huqooq-al-Ibad), Allah(S.W.T) will be pleased with you.
But remember, no matter how much good you do or the whole creation together does, it will not add anything to Him(S.W.T). Likewise the opposite is true.
It is the creation who would benefit by submitting to Him alone.
If you want about the specific things that are mentioned in literature(Hadith), where it has been said that the reward of this would be equivalent to that, just Google about it you would find plenty of material.