Haggai 2:7 mentions "the Desire of all Nations", according to modern day Judaism, is this a reference to the Messiah or to God Himself?
This translation might help explain the phrase
And I will shake up all the nations, and they shall come [with] the precious things of all the nations. And I will fill this House with glory, said the Lord of Hosts.
The translation (Judaica Press) jibes with the 1917 JPS translation
And I will shake all nations, and the choicest things of all nations shall come, and I will fill this house with glory, saith HaShem of hosts
The reference is to neither a messiah or God, but to the desirable things brought by the other nations (detailed in verse 8 as, for example, gold and silver).